Pub Date : 2024-02-01DOI: 10.1088/1674-4926/45/2/022801
Zhe He, Gentian Yue, Yueyue Gao, Chen Dong, Furui Tan
The TiO2 with nanoparticles (NPs), nanowires (NWs), nanorods (NRs) and nanotubes (NTs) structures were prepared by using a in-situ hydrothermal technique, and then proposed as a photoanode for flexible dye-sensitized solar cell (FDSSC). The influences of the morphology of TiO2 on the photovoltaic performances of FDSSCs were investigated. Under rear illumination of 100 mW·cm−2, the power conversion efficiencies of FDSSCs achieved 6.96%, 7.36%, 7.65%, and 7.83% with the TiO2 photoanodes of NPs, NWs, NRs, and NTs and PEDOT counter electrode. The FDSSCs based on TiO2 NRs and NTs photoanodes have higher short circuit current densities and power conversion efficiencies than that of the others. The enhanced power conversion efficiency is responsible for their nanotubes and rod-shaped ordered structures, which are more beneficial to transmission of electron and hole in semiconductor compared to the TiO2 nanoparticles and nanowires disordered structure.
{"title":"Efficient flexible dye-sensitized solar cells from rear illumination based on different morphologies of titanium dioxide photoanode","authors":"Zhe He, Gentian Yue, Yueyue Gao, Chen Dong, Furui Tan","doi":"10.1088/1674-4926/45/2/022801","DOIUrl":"https://doi.org/10.1088/1674-4926/45/2/022801","url":null,"abstract":"The TiO<sub>2</sub> with nanoparticles (NPs), nanowires (NWs), nanorods (NRs) and nanotubes (NTs) structures were prepared by using a <italic toggle=\"yes\">in-situ</italic> hydrothermal technique, and then proposed as a photoanode for flexible dye-sensitized solar cell (FDSSC). The influences of the morphology of TiO<sub>2</sub> on the photovoltaic performances of FDSSCs were investigated. Under rear illumination of 100 mW·cm<sup>−2</sup>, the power conversion efficiencies of FDSSCs achieved 6.96%, 7.36%, 7.65%, and 7.83% with the TiO<sub>2</sub> photoanodes of NPs, NWs, NRs, and NTs and PEDOT counter electrode. The FDSSCs based on TiO<sub>2</sub> NRs and NTs photoanodes have higher short circuit current densities and power conversion efficiencies than that of the others. The enhanced power conversion efficiency is responsible for their nanotubes and rod-shaped ordered structures, which are more beneficial to transmission of electron and hole in semiconductor compared to the TiO<sub>2</sub> nanoparticles and nanowires disordered structure.","PeriodicalId":17038,"journal":{"name":"Journal of Semiconductors","volume":"2 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-01DOI: 10.1088/1674-4926/45/2/022501
Peng Wu, Jianping Liu, Lei Hu, Xiaoyu Ren, Aiqin Tian, Wei Zhou, Fan Zhang, Xuan Li, Masao Ikeda, Hui Yang
A new kind of step-flow growth mode is proposed, which adopts sidewall as step source on patterned GaN substrate. The terrace width of steps originated from the sidewall was found to change with the growth temperature and ammonia flux. The growth mechanism is explained and simulated based on step motion model. This work helps better understand the behaviors of step advancement and puts forward a method of precisely modulating atomic steps.
{"title":"Controllable step-flow growth of GaN on patterned freestanding substrate","authors":"Peng Wu, Jianping Liu, Lei Hu, Xiaoyu Ren, Aiqin Tian, Wei Zhou, Fan Zhang, Xuan Li, Masao Ikeda, Hui Yang","doi":"10.1088/1674-4926/45/2/022501","DOIUrl":"https://doi.org/10.1088/1674-4926/45/2/022501","url":null,"abstract":"A new kind of step-flow growth mode is proposed, which adopts sidewall as step source on patterned GaN substrate. The terrace width of steps originated from the sidewall was found to change with the growth temperature and ammonia flux. The growth mechanism is explained and simulated based on step motion model. This work helps better understand the behaviors of step advancement and puts forward a method of precisely modulating atomic steps.","PeriodicalId":17038,"journal":{"name":"Journal of Semiconductors","volume":"103 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, a two-step metal organic chemical vapor deposition (MOCVD) method was applied for growing β-Ga2O3 film on c-plane sapphire. Optimized buffer layer growth temperature (TB) was found at 700 °C and the β-Ga2O3 film with full width at half maximum (FWHM) of 0.66° was achieved. A metal−semiconductor−metal (MSM) solar-blind photodetector (PD) was fabricated based on the β-Ga2O3 film. Ultrahigh responsivity of 1422 A/W @ 254 nm and photo-to-dark current ratio (PDCR) of 106 at 10 V bias were obtained. The detectivity of 2.5 × 1015 Jones proved that the photodetector has outstanding performance in detecting weak signals. Moreover, the photodetector exhibited superior wavelength selectivity with rejection ratio (R250 nm/R400 nm) of 105. These results indicate that the two-step method is a promising approach for preparation of high-quality β-Ga2O3 films for high-performance solar-blind photodetectors.
{"title":"Two-step growth of β-Ga2O3 on c-plane sapphire using MOCVD for solar-blind photodetector","authors":"Peipei Ma, Jun Zheng, Xiangquan Liu, Zhi Liu, Yuhua Zuo, Buwen Cheng","doi":"10.1088/1674-4926/45/2/022502","DOIUrl":"https://doi.org/10.1088/1674-4926/45/2/022502","url":null,"abstract":"In this work, a two-step metal organic chemical vapor deposition (MOCVD) method was applied for growing <italic toggle=\"yes\">β</italic>-Ga<sub>2</sub>O<sub>3</sub> film on <italic toggle=\"yes\">c</italic>-plane sapphire. Optimized buffer layer growth temperature (<italic toggle=\"yes\">T</italic>\u0000<sub>B</sub>) was found at 700 °C and the <italic toggle=\"yes\">β</italic>-Ga<sub>2</sub>O<sub>3</sub> film with full width at half maximum (FWHM) of 0.66° was achieved. A metal−semiconductor−metal (MSM) solar-blind photodetector (PD) was fabricated based on the <italic toggle=\"yes\">β</italic>-Ga<sub>2</sub>O<sub>3</sub> film. Ultrahigh responsivity of 1422 A/W @ 254 nm and photo-to-dark current ratio (PDCR) of 10<sup>6</sup> at 10 V bias were obtained. The detectivity of 2.5 × 10<sup>15</sup> Jones proved that the photodetector has outstanding performance in detecting weak signals. Moreover, the photodetector exhibited superior wavelength selectivity with rejection ratio (<italic toggle=\"yes\">R</italic>\u0000<sub>250 nm</sub>/<italic toggle=\"yes\">R</italic>\u0000<sub>400 nm</sub>) of 10<sup>5</sup>. These results indicate that the two-step method is a promising approach for preparation of high-quality <italic toggle=\"yes\">β</italic>-Ga<sub>2</sub>O<sub>3</sub> films for high-performance solar-blind photodetectors.","PeriodicalId":17038,"journal":{"name":"Journal of Semiconductors","volume":"6 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139762016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new theoretical method to study super-multiperiod superlattices has been developed. The method combines the precision of the 8-band kp-method with the flexibility of the shooting method and the Monte Carlo approach. This method was applied to examine the finest quality samples of super-multiperiod Al0.3Ga0.7As/GaAs superlattices grown by molecular beam epitaxy. The express photoreflectance spectroscopy method was utilized to validate the proposed theoretical method. For the first time, the accurate theoretical analysis of the energy band diagram of super-multiperiod superlattices with experimental verification has been conducted. The proposed approach highly accurately determines transition peak positions and enables the calculation of the energy band diagram, transition energies, relaxation rates, and gain estimation. It has achieved a remarkably low 5% error compared to the commonly used method, which typically results in a 25% error, and allowed to recover the superlattice parameters. The retrieved intrinsic parameters of the samples aligned with XRD data and growth parameters. The proposed method also accurately predicted the escape of the second energy level for quantum well thicknesses less than 5 nm, as was observed in photoreflectance experiments. The new designs of THz light-emitting devices operating at room temperature were suggested by the developed method.
{"title":"An advanced theoretical approach to study super-multiperiod superlattices: theory vs experiments","authors":"Alexander Sergeevich Dashkov, Semyon Andreevich Khakhulin, Dmitrii Alekseevich Shapran, Gennadii Fedorovich Glinskii, Nikita Andreevich Kostromin, Alexander Leonidovich Vasiliev, Sergey Nikolayevich Yakunin, Oleg Sergeevich Komkov, Evgeniy Viktorovich Pirogov, Maxim Sergeevich Sobolev, Leonid Ivanovich Goray, Alexei Dmitrievich Bouravleuv","doi":"10.1088/1674-4926/45/2/022701","DOIUrl":"https://doi.org/10.1088/1674-4926/45/2/022701","url":null,"abstract":"A new theoretical method to study super-multiperiod superlattices has been developed. The method combines the precision of the 8-band <italic toggle=\"yes\">kp</italic>-method with the flexibility of the shooting method and the Monte Carlo approach. This method was applied to examine the finest quality samples of super-multiperiod Al<sub>0.3</sub>Ga<sub>0.7</sub>As/GaAs superlattices grown by molecular beam epitaxy. The express photoreflectance spectroscopy method was utilized to validate the proposed theoretical method. For the first time, the accurate theoretical analysis of the energy band diagram of super-multiperiod superlattices with experimental verification has been conducted. The proposed approach highly accurately determines transition peak positions and enables the calculation of the energy band diagram, transition energies, relaxation rates, and gain estimation. It has achieved a remarkably low 5% error compared to the commonly used method, which typically results in a 25% error, and allowed to recover the superlattice parameters. The retrieved intrinsic parameters of the samples aligned with XRD data and growth parameters. The proposed method also accurately predicted the escape of the second energy level for quantum well thicknesses less than 5 nm, as was observed in photoreflectance experiments. The new designs of THz light-emitting devices operating at room temperature were suggested by the developed method.","PeriodicalId":17038,"journal":{"name":"Journal of Semiconductors","volume":"3 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-01DOI: 10.1088/1674-4926/45/2/021801
Mingyuan Ye, Xiaorui Hao, Jinfeng Zeng, Lin Li, Pengfei Wang, Chenglin Zhang, Li Liu, Fanian Shi, Yuhan Wu
Anode materials are an essential part of lithium-ion batteries (LIBs), which determine the performance and safety of LIBs. Currently, graphite, as the anode material of commercial LIBs, is limited by its low theoretical capacity of 372 mA·h·g−1, thus hindering further development toward high-capacity and large-scale applications. Alkaline earth metal iron-based oxides are considered a promising candidate to replace graphite because of their low preparation cost, good thermal stability, superior stability, and high electrochemical performance. Nonetheless, many issues and challenges remain to be addressed. Herein, we systematically summarize the research progress of alkaline earth metal iron-based oxides as LIB anodes. Meanwhile, the material and structural properties, synthesis methods, electrochemical reaction mechanisms, and improvement strategies are introduced. Finally, existing challenges and future research directions are discussed to accelerate their practical application in commercial LIBs.
{"title":"Research progress of alkaline earth metal iron-based oxides as anodes for lithium-ion batteries","authors":"Mingyuan Ye, Xiaorui Hao, Jinfeng Zeng, Lin Li, Pengfei Wang, Chenglin Zhang, Li Liu, Fanian Shi, Yuhan Wu","doi":"10.1088/1674-4926/45/2/021801","DOIUrl":"https://doi.org/10.1088/1674-4926/45/2/021801","url":null,"abstract":"Anode materials are an essential part of lithium-ion batteries (LIBs), which determine the performance and safety of LIBs. Currently, graphite, as the anode material of commercial LIBs, is limited by its low theoretical capacity of 372 mA·h·g<sup>−1</sup>, thus hindering further development toward high-capacity and large-scale applications. Alkaline earth metal iron-based oxides are considered a promising candidate to replace graphite because of their low preparation cost, good thermal stability, superior stability, and high electrochemical performance. Nonetheless, many issues and challenges remain to be addressed. Herein, we systematically summarize the research progress of alkaline earth metal iron-based oxides as LIB anodes. Meanwhile, the material and structural properties, synthesis methods, electrochemical reaction mechanisms, and improvement strategies are introduced. Finally, existing challenges and future research directions are discussed to accelerate their practical application in commercial LIBs.","PeriodicalId":17038,"journal":{"name":"Journal of Semiconductors","volume":"37 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
(Ga,Fe)Sb is a promising magnetic semiconductor (MS) for spintronic applications because its Curie temperature (TC) is above 300 K when the Fe concentration is higher than 20%. However, the anisotropy constant Ku of (Ga,Fe)Sb is below 7.6 × 103 erg/cm3 when Fe concentration is lower than 30%, which is one order of magnitude lower than that of (Ga,Mn)As. To address this issue, we grew Ga1-x-yFexNiySb films with almost the same x (≈24%) and different y to characterize their magnetic and electrical transport properties. We found that the magnetic anisotropy of Ga0.76-yFe0.24NiySb can be enhanced by increasing y, in which Ku is negligible at y = 1.7% but increases to 3.8 × 105 erg/cm3 at y = 6.1% (TC = 354 K). In addition, the hole mobility (µ) of Ga1-x-yFexNiySb reaches 31.3 cm2/(V∙s) at x = 23.7%, y = 1.7% (TC = 319 K), which is much higher than the mobility of Ga1-xFexSb at x = 25.2% (µ = 6.2 cm2/(V∙s)). Our results provide useful information for enhancing the magnetic anisotropy and hole mobility of (Ga,Fe)Sb by using Ni co-doping.
(Ga,Fe)Sb是一种很有前途的自旋电子应用磁性半导体（MS），因为当铁元素浓度高于20%时，它的居里温度（TC）高于300 K。然而，当铁元素浓度低于 30% 时，(Ga,Fe)Sb 的各向异性常数 Ku 低于 7.6 × 103 erg/cm3，比 (Ga,Mn)As 低一个数量级。为了解决这个问题，我们生长了几乎相同 x（≈24%）和不同 y 的 Ga1-x-yFexNiySb 薄膜，以表征它们的磁性和电传输特性。我们发现，Ga0.76-yFe0.24NiySb 的磁各向异性可随着 y 的增加而增强，其中在 y = 1.7% 时，Ku 可忽略不计，但在 y = 6.1% 时（TC = 354 K），Ku 增加到 3.8 × 105 erg/cm3。此外，Ga1-x-yFexNiySb 的空穴迁移率（µ）在 x = 23.7%、y = 1.7%（TC = 319 K）时达到 31.3 cm2/（V∙s），远高于 Ga1-xFexSb 在 x = 25.2%（µ = 6.2 cm2/（V∙s））时的迁移率。我们的研究结果为通过掺杂镍来提高（Ga,Fe）Sb 的磁各向异性和空穴迁移率提供了有用的信息。
{"title":"Enhanced magnetic anisotropy and high hole mobility in magnetic semiconductor Ga1-x-y Fe x Ni y Sb","authors":"Zhi Deng, Hailong Wang, Qiqi Wei, Lei Liu, Hongli Sun, Dong Pan, Dahai Wei, Jianhua Zhao","doi":"10.1088/1674-4926/45/1/012101","DOIUrl":"https://doi.org/10.1088/1674-4926/45/1/012101","url":null,"abstract":"(Ga,Fe)Sb is a promising magnetic semiconductor (MS) for spintronic applications because its Curie temperature (<italic toggle=\"yes\">T</italic>\u0000<sub>C</sub>) is above 300 K when the Fe concentration is higher than 20%. However, the anisotropy constant <italic toggle=\"yes\">K</italic>\u0000<sub>u</sub> of (Ga,Fe)Sb is below 7.6 × 10<sup>3</sup> erg/cm<sup>3</sup> when Fe concentration is lower than 30%, which is one order of magnitude lower than that of (Ga,Mn)As. To address this issue, we grew Ga<sub>1-<italic toggle=\"yes\">x</italic>-<italic toggle=\"yes\">y</italic>\u0000</sub>Fe<sub>\u0000<italic toggle=\"yes\">x</italic>\u0000</sub>Ni<sub>\u0000<italic toggle=\"yes\">y</italic>\u0000</sub>Sb films with almost the same <italic toggle=\"yes\">x</italic> (≈24%) and different <italic toggle=\"yes\">y</italic> to characterize their magnetic and electrical transport properties. We found that the magnetic anisotropy of Ga<sub>0.76-<italic toggle=\"yes\">y</italic>\u0000</sub>Fe<sub>0.24</sub>Ni<sub>\u0000<italic toggle=\"yes\">y</italic>\u0000</sub>Sb can be enhanced by increasing <italic toggle=\"yes\">y</italic>, in which <italic toggle=\"yes\">K</italic>\u0000<sub>u</sub> is negligible at <italic toggle=\"yes\">y</italic> = 1.7% but increases to 3.8 × 10<sup>5</sup> erg/cm<sup>3</sup> at <italic toggle=\"yes\">y</italic> = 6.1% (<italic toggle=\"yes\">T</italic>\u0000<sub>C</sub> = 354 K). In addition, the hole mobility (<italic toggle=\"yes\">µ</italic>) of Ga<sub>1-<italic toggle=\"yes\">x</italic>-<italic toggle=\"yes\">y</italic>\u0000</sub>Fe<sub>\u0000<italic toggle=\"yes\">x</italic>\u0000</sub>Ni<sub>\u0000<italic toggle=\"yes\">y</italic>\u0000</sub>Sb reaches 31.3 cm<sup>2</sup>/(V∙s) at <italic toggle=\"yes\">x</italic> = 23.7%, <italic toggle=\"yes\">y</italic> = 1.7% (<italic toggle=\"yes\">T</italic>\u0000<sub>C</sub> = 319 K), which is much higher than the mobility of Ga<sub>1-<italic toggle=\"yes\">x</italic>\u0000</sub>Fe<sub>\u0000<italic toggle=\"yes\">x</italic>\u0000</sub>Sb at <italic toggle=\"yes\">x</italic> = 25.2% (<italic toggle=\"yes\">µ</italic> = 6.2 cm<sup>2</sup>/(V∙s)). Our results provide useful information for enhancing the magnetic anisotropy and hole mobility of (Ga,Fe)Sb by using Ni co-doping.","PeriodicalId":17038,"journal":{"name":"Journal of Semiconductors","volume":"72 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139510045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article presents an 8-element dual-polarized phased-array transceiver (TRX) front-end IC for millimeter-wave (mm-Wave) 5G new radio (NR). Power enhancement technologies for power amplifiers (PA) in mm-Wave 5G phased-array TRX are discussed. A four-stage wideband high-power class-AB PA with distributed-active-transformer (DAT) power combining and multi-stage second-harmonic traps is proposed, ensuring the mitigated amplitude-to-phase (AM-PM) distortions across wide carrier frequencies without degrading transmitting (TX) power, gain and efficiency. TX and receiving (RX) switching is achieved by a matching network co-designed on-chip T/R switch. In each TRX element, 6-bit 360° phase shifting and 6-bit 31.5-dB gain tuning are respectively achieved by the digital-controlled vector-modulated phase shifter (VMPS) and differential attenuator (ATT). Fabricated in 65-nm bulk complementary metal oxide semiconductor (CMOS), the proposed TRX demonstrates the measured peak TX/RX gains of 25.5/21.3 dB, covering the 24−29.5 GHz band. The measured peak TX OP1dB and power-added efficiency (PAE) are 20.8 dBm and 21.1%, respectively. The measured minimum RX NF is 4.1 dB. The TRX achieves an output power of 11.0−12.4 dBm and error vector magnitude (EVM) of 5% with 400-MHz 5G NR FR2 OFDM 64-QAM signals across 24−29.5 GHz, covering 3GPP 5G NR FR2 operating bands of n257, n258, and n261.
{"title":"A 24−30 GHz 8-element dual-polarized 5G FR2 phased-array transceiver IC with 20.8-dBm TX OP1dB and 4.1-dB RX NFin 65-nm CMOS","authors":"Yongran Yi, Dixian Zhao, Jiajun Zhang, Peng Gu, Chenyu Xu, Yuan Chai, Huiqi Liu, Xiaohu You","doi":"10.1088/1674-4926/45/1/012201","DOIUrl":"https://doi.org/10.1088/1674-4926/45/1/012201","url":null,"abstract":"This article presents an 8-element dual-polarized phased-array transceiver (TRX) front-end IC for millimeter-wave (mm-Wave) 5G new radio (NR). Power enhancement technologies for power amplifiers (PA) in mm-Wave 5G phased-array TRX are discussed. A four-stage wideband high-power class-AB PA with distributed-active-transformer (DAT) power combining and multi-stage second-harmonic traps is proposed, ensuring the mitigated amplitude-to-phase (AM-PM) distortions across wide carrier frequencies without degrading transmitting (TX) power, gain and efficiency. TX and receiving (RX) switching is achieved by a matching network co-designed on-chip T/R switch. In each TRX element, 6-bit 360° phase shifting and 6-bit 31.5-dB gain tuning are respectively achieved by the digital-controlled vector-modulated phase shifter (VMPS) and differential attenuator (ATT). Fabricated in 65-nm bulk complementary metal oxide semiconductor (CMOS), the proposed TRX demonstrates the measured peak TX/RX gains of 25.5/21.3 dB, covering the 24−29.5 GHz band. The measured peak TX OP1dB and power-added efficiency (PAE) are 20.8 dBm and 21.1%, respectively. The measured minimum RX NF is 4.1 dB. The TRX achieves an output power of 11.0−12.4 dBm and error vector magnitude (EVM) of 5% with 400-MHz 5G NR FR2 OFDM 64-QAM signals across 24−29.5 GHz, covering 3GPP 5G NR FR2 operating bands of n257, n258, and n261.","PeriodicalId":17038,"journal":{"name":"Journal of Semiconductors","volume":"44 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139509910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two-dimensional (2D) WSe2 has received increasing attention due to its unique optical properties and bipolar behavior. Several WSe2-based heterojunctions exhibit bidirectional rectification characteristics, but most devices have a lower rectification ratio. In this work, the Bi2O2Se/WSe2 heterojunction prepared by us has a type Ⅱ band alignment, which can vastly suppress the channel current through the interface barrier so that the Bi2O2Se/WSe2 heterojunction device has a large rectification ratio of about 105. Meanwhile, under different gate voltage modulation, the current on/off ratio of the device changes by nearly five orders of magnitude, and the maximum current on/off ratio is expected to be achieved 106. The photocurrent measurement reveals the behavior of recombination and space charge confinement, further verifying the bidirectional rectification behavior of heterojunctions, and it also exhibits excellent performance in light response. In the future, Bi2O2Se/WSe2 heterojunction field-effect transistors have great potential to reduce the volume of integrated circuits as a bidirectional controlled switching device.
{"title":"Bidirectional rectifier with gate voltage control based on Bi2O2Se/WSe2 heterojunction","authors":"Ruonan Li, Fangchao Lu, Jiajun Deng, Xingqiu Fu, Wenjie Wang, He Tian","doi":"10.1088/1674-4926/45/1/012701","DOIUrl":"https://doi.org/10.1088/1674-4926/45/1/012701","url":null,"abstract":"Two-dimensional (2D) WSe<sub>2</sub> has received increasing attention due to its unique optical properties and bipolar behavior. Several WSe<sub>2</sub>-based heterojunctions exhibit bidirectional rectification characteristics, but most devices have a lower rectification ratio. In this work, the Bi<sub>2</sub>O<sub>2</sub>Se/WSe<sub>2</sub> heterojunction prepared by us has a type Ⅱ band alignment, which can vastly suppress the channel current through the interface barrier so that the Bi<sub>2</sub>O<sub>2</sub>Se/WSe<sub>2</sub> heterojunction device has a large rectification ratio of about 10<sup>5</sup>. Meanwhile, under different gate voltage modulation, the current on/off ratio of the device changes by nearly five orders of magnitude, and the maximum current on/off ratio is expected to be achieved 10<sup>6</sup>. The photocurrent measurement reveals the behavior of recombination and space charge confinement, further verifying the bidirectional rectification behavior of heterojunctions, and it also exhibits excellent performance in light response. In the future, Bi<sub>2</sub>O<sub>2</sub>Se/WSe<sub>2</sub> heterojunction field-effect transistors have great potential to reduce the volume of integrated circuits as a bidirectional controlled switching device.","PeriodicalId":17038,"journal":{"name":"Journal of Semiconductors","volume":"10 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139509844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the rapid development of machine learning, the demand for high-efficient computing becomes more and more urgent. To break the bottleneck of the traditional Von Neumann architecture, computing-in-memory (CIM) has attracted increasing attention in recent years. In this work, to provide a feasible CIM solution for the large-scale neural networks (NN) requiring continuous weight updating in online training, a flash-based computing-in-memory with high endurance (109 cycles) and ultra-fast programming speed is investigated. On the one hand, the proposed programming scheme of channel hot electron injection (CHEI) and hot hole injection (HHI) demonstrate high linearity, symmetric potentiation, and a depression process, which help to improve the training speed and accuracy. On the other hand, the low-damage programming scheme and memory window (MW) optimizations can suppress cell degradation effectively with improved computing accuracy. Even after 109 cycles, the leakage current (Ioff) of cells remains sub-10pA, ensuring the large-scale computing ability of memory. Further characterizations are done on read disturb to demonstrate its robust reliabilities. By processing CIFAR-10 tasks, it is evident that ~90% accuracy can be achieved after 109 cycles in both ResNet50 and VGG16 NN. Our results suggest that flash-based CIM has great potential to overcome the limitations of traditional Von Neumann architectures and enable high-performance NN online training, which pave the way for further development of artificial intelligence (AI) accelerators.
{"title":"Optimized operation scheme of flash-memory-based neural network online training with ultra-high endurance","authors":"Yang Feng, Zhaohui Sun, Yueran Qi, Xuepeng Zhan, Junyu Zhang, Jing Liu, Masaharu Kobayashi, Jixuan Wu, Jiezhi Chen","doi":"10.1088/1674-4926/45/1/012301","DOIUrl":"https://doi.org/10.1088/1674-4926/45/1/012301","url":null,"abstract":"With the rapid development of machine learning, the demand for high-efficient computing becomes more and more urgent. To break the bottleneck of the traditional Von Neumann architecture, computing-in-memory (CIM) has attracted increasing attention in recent years. In this work, to provide a feasible CIM solution for the large-scale neural networks (NN) requiring continuous weight updating in online training, a flash-based computing-in-memory with high endurance (10<sup>9</sup> cycles) and ultra-fast programming speed is investigated. On the one hand, the proposed programming scheme of channel hot electron injection (CHEI) and hot hole injection (HHI) demonstrate high linearity, symmetric potentiation, and a depression process, which help to improve the training speed and accuracy. On the other hand, the low-damage programming scheme and memory window (MW) optimizations can suppress cell degradation effectively with improved computing accuracy. Even after 10<sup>9</sup> cycles, the leakage current (<italic toggle=\"yes\">I</italic>\u0000<sub>off</sub>) of cells remains sub-10pA, ensuring the large-scale computing ability of memory. Further characterizations are done on read disturb to demonstrate its robust reliabilities. By processing CIFAR-10 tasks, it is evident that ~90% accuracy can be achieved after 10<sup>9</sup> cycles in both ResNet50 and VGG16 NN. Our results suggest that flash-based CIM has great potential to overcome the limitations of traditional Von Neumann architectures and enable high-performance NN online training, which pave the way for further development of artificial intelligence (AI) accelerators.","PeriodicalId":17038,"journal":{"name":"Journal of Semiconductors","volume":"70 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139509891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-01DOI: 10.1088/1674-4926/45/1/012503
Jun Fang, Fan Zhang, Wenxian Yang, Aiqin Tian, Jianping Liu, Shulong Lu, Hui Yang
The InGaN films and GaN/InGaN/GaN tunnel junctions (TJs) were grown on GaN templates with plasma-assisted molecular beam epitaxy. As the In content increases, the quality of InGaN films grown on GaN templates decreases and the surface roughness of the samples increases. V-pits and trench defects were not found in the AFM images. p++-GaN/InGaN/n++-GaN TJs were investigated for various In content, InGaN thicknesses and doping concentration in the InGaN insert layer. The InGaN insert layer can promote good interband tunneling in GaN/InGaN/GaN TJ and significantly reduce operating voltage when doping is sufficiently high. The current density increases with increasing In content for the 3 nm InGaN insert layer, which is achieved by reducing the depletion zone width and the height of the potential barrier. At a forward current density of 500 A/cm2, the measured voltage was 4.31 V and the differential resistance was measured to be 3.75 × 10−3 Ω·cm2 for the device with a 3 nm p++-In0.35Ga0.65N insert layer. When the thickness of the In0.35Ga0.65N layer is closer to the “balanced” thickness, the TJ current density is higher. If the thickness is too high or too low, the width of the depletion zone will increase and the current density will decrease. The undoped InGaN layer has a better performance than n-type doping in the TJ. Polarization-engineered tunnel junctions can enhance the functionality and performance of electronic and optoelectronic devices.
{"title":"Electrical properties and structural optimization of GaN/InGaN/GaN tunnel junctions grown by molecular beam epitaxy","authors":"Jun Fang, Fan Zhang, Wenxian Yang, Aiqin Tian, Jianping Liu, Shulong Lu, Hui Yang","doi":"10.1088/1674-4926/45/1/012503","DOIUrl":"https://doi.org/10.1088/1674-4926/45/1/012503","url":null,"abstract":"The InGaN films and GaN/InGaN/GaN tunnel junctions (TJs) were grown on GaN templates with plasma-assisted molecular beam epitaxy. As the In content increases, the quality of InGaN films grown on GaN templates decreases and the surface roughness of the samples increases. V-pits and trench defects were not found in the AFM images. p<sup>++</sup>-GaN/InGaN/n<sup>++</sup>-GaN TJs were investigated for various In content, InGaN thicknesses and doping concentration in the InGaN insert layer. The InGaN insert layer can promote good interband tunneling in GaN/InGaN/GaN TJ and significantly reduce operating voltage when doping is sufficiently high. The current density increases with increasing In content for the 3 nm InGaN insert layer, which is achieved by reducing the depletion zone width and the height of the potential barrier. At a forward current density of 500 A/cm<sup>2</sup>, the measured voltage was 4.31 V and the differential resistance was measured to be 3.75 × 10<sup>−3</sup> Ω·cm<sup>2</sup> for the device with a 3 nm p<sup>++</sup>-In<sub>0.35</sub>Ga<sub>0.65</sub>N insert layer. When the thickness of the In<sub>0.35</sub>Ga<sub>0.65</sub>N layer is closer to the “balanced” thickness, the TJ current density is higher. If the thickness is too high or too low, the width of the depletion zone will increase and the current density will decrease. The undoped InGaN layer has a better performance than n-type doping in the TJ. Polarization-engineered tunnel junctions can enhance the functionality and performance of electronic and optoelectronic devices.","PeriodicalId":17038,"journal":{"name":"Journal of Semiconductors","volume":"12 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139509724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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