Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237197
H. Yoshida, Y. Terada, H. Miyake, K. Hiramatsu
Self-organized GaN nanotips, which were nanoscale tip-shaped pillar structure, were fabricated by reactive ion etching using chlorine plasma. It has been found that the structure has a two-dimensional isotropic distribution with broadband periodicity of subwavelength from the ultraviolet (UV) to the visible (VIS) region by Fourier transform analysis. The nanotips exhibited a diameter of approximately 20 nm, a most frequent periodicity of 96 nm and a height of approximately 200 nm on the GaN surface. The reflectance of the nanotip surface was significantly suppressed to less than 0.01 compared with 0.3 of the smooth surface in UV region. The transmittance was also improved approximately 12% at longer wavelength than the band edge (/spl sim/365 nm). We have found that the nanotip surface provides antireflection and enhanced transmission effects from the UV to the VIS region (300 nm to 900 nm). These excellent antireflective-properties of the self-organized GaN nanotips are expected to improve the performances of light-emitting and photo-detective devices.
{"title":"Antireflection structure of self-organized GaN nanotips","authors":"H. Yoshida, Y. Terada, H. Miyake, K. Hiramatsu","doi":"10.1109/COMMAD.2002.1237197","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237197","url":null,"abstract":"Self-organized GaN nanotips, which were nanoscale tip-shaped pillar structure, were fabricated by reactive ion etching using chlorine plasma. It has been found that the structure has a two-dimensional isotropic distribution with broadband periodicity of subwavelength from the ultraviolet (UV) to the visible (VIS) region by Fourier transform analysis. The nanotips exhibited a diameter of approximately 20 nm, a most frequent periodicity of 96 nm and a height of approximately 200 nm on the GaN surface. The reflectance of the nanotip surface was significantly suppressed to less than 0.01 compared with 0.3 of the smooth surface in UV region. The transmittance was also improved approximately 12% at longer wavelength than the band edge (/spl sim/365 nm). We have found that the nanotip surface provides antireflection and enhanced transmission effects from the UV to the VIS region (300 nm to 900 nm). These excellent antireflective-properties of the self-organized GaN nanotips are expected to improve the performances of light-emitting and photo-detective devices.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"239 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121891868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237204
A. Motogaito, K. Ohta, H. Watanabe, K. Hiramatsu, Y. Ohuchi, K. Tadatomo, Y. Hamamura, K. Fukui
Responsivity spectra and electrical characteristics of GaN based Schottky type ultraviolet (UV) photodetectors with transparent electrode from the near UV region to the vacuum ultraviolet (VUV) region (3.4 to 25 eV) are described. In order to improve device performance in applying reverse bias, the annealed transparent Schottky electrode in N/sub 2/ ambient is used. The dark current of samples after annealing Schottky electrode is reduced by hundredth part of that of samples before annealing Schottky electrode. The responsivity spectra with reverse bias are improved by annealing Schottky electrode.
{"title":"Responsivity and electrical characteristics of GaN based Schottky barrier UV detectors with transparent electrode in the near UV and VUV region","authors":"A. Motogaito, K. Ohta, H. Watanabe, K. Hiramatsu, Y. Ohuchi, K. Tadatomo, Y. Hamamura, K. Fukui","doi":"10.1109/COMMAD.2002.1237204","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237204","url":null,"abstract":"Responsivity spectra and electrical characteristics of GaN based Schottky type ultraviolet (UV) photodetectors with transparent electrode from the near UV region to the vacuum ultraviolet (VUV) region (3.4 to 25 eV) are described. In order to improve device performance in applying reverse bias, the annealed transparent Schottky electrode in N/sub 2/ ambient is used. The dark current of samples after annealing Schottky electrode is reduced by hundredth part of that of samples before annealing Schottky electrode. The responsivity spectra with reverse bias are improved by annealing Schottky electrode.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124017564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237286
C. A. Freeth, R. Lewis
Shallow impurity states of donors and acceptors in Ge have been investigated by far-infrared laser magnetospectroscopy. The Zeeman splitting of the impurity states produces resonant absorption of the laser radiation at certain magnetic fields. The data are compared to measurements made using a conventional spectrometer and good agreement is found.
{"title":"Selective laser excitation spectroscopy of gallium and phosphorous in germanium","authors":"C. A. Freeth, R. Lewis","doi":"10.1109/COMMAD.2002.1237286","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237286","url":null,"abstract":"Shallow impurity states of donors and acceptors in Ge have been investigated by far-infrared laser magnetospectroscopy. The Zeeman splitting of the impurity states produces resonant absorption of the laser radiation at certain magnetic fields. The data are compared to measurements made using a conventional spectrometer and good agreement is found.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124424235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237177
M. Shur
In AlN/InN/GaN-based semiconductors, the polar optical phonon energy is large (much larger than the thermal energy at room temperature). As a consequence, the dominant optical polar scattering occurs in two steps: photon absorption and re-emission (resulting in an effectively elastic scattering process). In high electric fields, an electron runaway plays a key role in determining the peak field and peak velocity in these compounds. The runaway effects are further enhanced in the two dimensional electron gas at the AlGaN/GaN or AlGaInN-InGaN heterointerfaces. As a result of the runaway and quantization effects, the peak electron drift velocity and peak electric field of the 2D electrons in compound semiconductors are smaller than for the 3D electrons in these materials. In very short (e.g. sub-0.1 micron) GaN-based structures, ballistic and overshoot effects become important. In a deep submicron structures, the ballistic effects in low electric fields reduce an apparent value of the low field mobility because of a finite electron acceleration time in the structure. In long channel devices, the electron mobility in AlGaN/GaN or AIGalnN/InGaN heterostructures at cryogenic temperatures is limited by acoustic scattering, electron transfer from 2D to 3D states, and by the alloy scattering. Relatively high values of the electron mobility and very high values of the 2D electron gas densities in nitride heterostructures also make them attractive candidates for plasma wave electronics devices operating in the terahertz range of frequencies.
{"title":"Physics of electron transport in nitride-based material","authors":"M. Shur","doi":"10.1109/COMMAD.2002.1237177","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237177","url":null,"abstract":"In AlN/InN/GaN-based semiconductors, the polar optical phonon energy is large (much larger than the thermal energy at room temperature). As a consequence, the dominant optical polar scattering occurs in two steps: photon absorption and re-emission (resulting in an effectively elastic scattering process). In high electric fields, an electron runaway plays a key role in determining the peak field and peak velocity in these compounds. The runaway effects are further enhanced in the two dimensional electron gas at the AlGaN/GaN or AlGaInN-InGaN heterointerfaces. As a result of the runaway and quantization effects, the peak electron drift velocity and peak electric field of the 2D electrons in compound semiconductors are smaller than for the 3D electrons in these materials. In very short (e.g. sub-0.1 micron) GaN-based structures, ballistic and overshoot effects become important. In a deep submicron structures, the ballistic effects in low electric fields reduce an apparent value of the low field mobility because of a finite electron acceleration time in the structure. In long channel devices, the electron mobility in AlGaN/GaN or AIGalnN/InGaN heterostructures at cryogenic temperatures is limited by acoustic scattering, electron transfer from 2D to 3D states, and by the alloy scattering. Relatively high values of the electron mobility and very high values of the 2D electron gas densities in nitride heterostructures also make them attractive candidates for plasma wave electronics devices operating in the terahertz range of frequencies.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128389169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237217
R. Sewell, J. Dell, C. Musca, L. Faraone, K. Prince
Steady-state lifetime of photogenerated minority carriers has been investigated in heterostructure HgCdTe devices fabricated on molecular beam epitaxy (MBE) grown material. A wider bandgap capping layer (Hg/sub 1-x/Cd/sub (x)/Te, x = 0.44) was grown on a narrower bandgap absorbing layer (Hg/sub 1-x/Cd/sub (x)/Te, x = 0.32, /spl lambda//sub ca,80 K/ = 4.6 /spl mu/m) material in an uninterrupted MBE growth to create an abrupt heterointerface. Steady-state lifetime as a function of temperature over the range 80 K to 300 K was extracted from photoconductive responsivity at an optical wavelength corresponding to the peak responsivity at that temperature. At 80 K, the photoconductors exhibit a specific detectivity of 4.5 /spl times/ 10/sup 11/ cmHz/sup -1/W/sup -1/ (chopping frequency of 1 kHz). For each measurement temperature, the steady-state excess carrier lifetime determined experimentally was compared to the theoretical bulk lifetime for material with x = 0.32 and effective n-type doping density of 3.7/spl times/ 10/sup 14/ cm/sup -3/. For temperatures below 180 K, the measured lifetime is in agreement with the calculated bulk lifetime for the absorbing layer of /spl sim/12 /spl mu/s; however, for higher temperatures there is evidence of an additional recombination mechanism which reduces the effective lifetime in the material. It is concluded that for temperatures above 180 K. there is significant thermally induced promotion of photogenerated carriers from the narrow bandgap absorbing layer into the wide bandgap capping layer, leading to a reduction in the responsivity of the detector due Io the lower excess carrier lifetime and relatively high doping of the wide bandgap layer.
在分子束外延 (MBE) 生长材料上制造的异质结构 HgCdTe 器件中，研究了光生少数载流子的稳态寿命。在不间断的分子束外延生长过程中，在较窄带隙吸收层（Hg/sub 1-x/Cd/sub (x)/Te, x = 0.32, /spl lambda//sub ca,80 K/ = 4.6 /spl mu/m）材料上生长了较宽带隙封顶层（Hg/sub 1-x/Cd/sub (x)/Te, x = 0.44），从而形成了一个突兀的异质界面。在 80 K 至 300 K 范围内，稳态寿命与温度的函数关系是从光电导响应率中提取的，光波长与该温度下的峰值响应率相对应。在 80 K 时，光电导体的特定检测率为 4.5 /spl times/ 10/sup 11/ cmHz/sup-1/W/sup-1/（斩波频率为 1 kHz）。在每个测量温度下，将实验测定的稳态过剩载流子寿命与 x = 0.32 且有效 n 型掺杂密度为 3.7/spl times/ 10/sup 14/ cm/sup -3/ 的材料的理论总体寿命进行比较。在低于 180 K 的温度下，测量的寿命与计算的吸收层总体寿命 /spl sim/12 /spl mu/s 一致；但在较高温度下，有证据表明存在额外的重组机制，从而降低了材料的有效寿命。结论是，当温度高于 180 K 时，窄带隙吸收层的光生载流子会在热诱导下大量进入宽带隙封顶层，从而导致探测器的响应率降低，原因是宽带隙层的过剩载流子寿命较短，掺杂程度相对较高。
{"title":"Minority carrier behaviour in abrupt MBE grown HgCdTe heterostructures","authors":"R. Sewell, J. Dell, C. Musca, L. Faraone, K. Prince","doi":"10.1109/COMMAD.2002.1237217","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237217","url":null,"abstract":"Steady-state lifetime of photogenerated minority carriers has been investigated in heterostructure HgCdTe devices fabricated on molecular beam epitaxy (MBE) grown material. A wider bandgap capping layer (Hg/sub 1-x/Cd/sub (x)/Te, x = 0.44) was grown on a narrower bandgap absorbing layer (Hg/sub 1-x/Cd/sub (x)/Te, x = 0.32, /spl lambda//sub ca,80 K/ = 4.6 /spl mu/m) material in an uninterrupted MBE growth to create an abrupt heterointerface. Steady-state lifetime as a function of temperature over the range 80 K to 300 K was extracted from photoconductive responsivity at an optical wavelength corresponding to the peak responsivity at that temperature. At 80 K, the photoconductors exhibit a specific detectivity of 4.5 /spl times/ 10/sup 11/ cmHz/sup -1/W/sup -1/ (chopping frequency of 1 kHz). For each measurement temperature, the steady-state excess carrier lifetime determined experimentally was compared to the theoretical bulk lifetime for material with x = 0.32 and effective n-type doping density of 3.7/spl times/ 10/sup 14/ cm/sup -3/. For temperatures below 180 K, the measured lifetime is in agreement with the calculated bulk lifetime for the absorbing layer of /spl sim/12 /spl mu/s; however, for higher temperatures there is evidence of an additional recombination mechanism which reduces the effective lifetime in the material. It is concluded that for temperatures above 180 K. there is significant thermally induced promotion of photogenerated carriers from the narrow bandgap absorbing layer into the wide bandgap capping layer, leading to a reduction in the responsivity of the detector due Io the lower excess carrier lifetime and relatively high doping of the wide bandgap layer.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129338240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237319
J. Tucker, L. Leng, A. Rakić
In this paper we report on a laser range finding system built using the self-mixing effect in a vertical-cavity surface-emitting laser (VCSEL). The distance to the target in these range finders is usually calculated by determining the time interval between the peaks in the resulting power fluctuations that are produced by the self-mixing effect. In this study we propose the use of a method that utilises the fast Fourier transform (FFT) that proves to have better performance than the traditional peak spacing methods used by other researchers. A range finding system has been built using a VCSEL and the FFT to measure a range of distances from 20 cm to 1 m with a maximum error of 1.5% and a resolution of 5 mm. This is the first time to our knowledge that such a range finding system has been built with a VCSEL.
本文报道了利用垂直腔面发射激光器(VCSEL)的自混合效应建立的激光测距系统。在这些测距仪中，到目标的距离通常是通过确定由自混合效应产生的功率波动峰值之间的时间间隔来计算的。在这项研究中，我们提出了一种利用快速傅里叶变换(FFT)的方法，该方法被证明比其他研究人员使用的传统峰间距方法具有更好的性能。利用VCSEL和FFT建立了测距系统，测量距离为20 cm ~ 1 m，最大误差为1.5%，分辨率为5 mm。据我们所知，这是第一次用VCSEL建立这样的测距系统。
{"title":"Laser range finding using the self-mixing effect in a vertical-cavity surface emitting laser","authors":"J. Tucker, L. Leng, A. Rakić","doi":"10.1109/COMMAD.2002.1237319","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237319","url":null,"abstract":"In this paper we report on a laser range finding system built using the self-mixing effect in a vertical-cavity surface-emitting laser (VCSEL). The distance to the target in these range finders is usually calculated by determining the time interval between the peaks in the resulting power fluctuations that are produced by the self-mixing effect. In this study we propose the use of a method that utilises the fast Fourier transform (FFT) that proves to have better performance than the traditional peak spacing methods used by other researchers. A range finding system has been built using a VCSEL and the FFT to measure a range of distances from 20 cm to 1 m with a maximum error of 1.5% and a resolution of 5 mm. This is the first time to our knowledge that such a range finding system has been built with a VCSEL.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132460937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237232
L. Jiang, Gao Zhong-yu, Dong Jingxin
It is difficult to acquire the actual mechanical parameters of comb-finger MEMS devices, for its sensing element has special structure. In order to derive the parameters, such as the proof mass m, the equivalent distance d/sub 0/ between fingers, and the mechanical stiffness k/sub m/, a static electrometric method is investigated. The method includes two experiments, the electrostatic force experiment and the open loop frequency response experiment, and the values of d/sub 0/, d/sub 0/, and k/sub m/ can be calculated with the electrical variables in the experiments. The experimental results show that the actual mechanical parameters of the sensing element can be estimated with a high accuracy. It is a convenient and useful method to be used in the fieldwork without the special requirement of environment and costly facilities.
{"title":"An electrometric method to measure the mechanical parameters of MEMS devices","authors":"L. Jiang, Gao Zhong-yu, Dong Jingxin","doi":"10.1109/COMMAD.2002.1237232","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237232","url":null,"abstract":"It is difficult to acquire the actual mechanical parameters of comb-finger MEMS devices, for its sensing element has special structure. In order to derive the parameters, such as the proof mass m, the equivalent distance d/sub 0/ between fingers, and the mechanical stiffness k/sub m/, a static electrometric method is investigated. The method includes two experiments, the electrostatic force experiment and the open loop frequency response experiment, and the values of d/sub 0/, d/sub 0/, and k/sub m/ can be calculated with the electrical variables in the experiments. The experimental results show that the actual mechanical parameters of the sensing element can be estimated with a high accuracy. It is a convenient and useful method to be used in the fieldwork without the special requirement of environment and costly facilities.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"681 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132519211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237235
K. Sae-tang, S. Somkuarnpanit, S. Khuntaweetep
This paper proposes a wavelength sensor using a section of curved optical waveguide. The finite-difference time-domain (FDTD) method is used in analysis of the field intensity of light propagating thorough the structure. Light with different wavelengths would propagate in different energy transmission, which allows to the technique to indicate the light wavelength. Parameters of the structure such as: w, T and R are appropriately considered. The device with a width of 0.6 /spl mu/m and thickness of 0.6 /spl mu/m provides the maximum light transmission. At the particular curve radius of 3 /spl mu/m, the structure could be employed to measure the communication wavelengths, in this case in a range between 1520 and 1580 nm, with a correlation factor of 99.82%. The wide band of wavelengths could possibly be carried out using a number of wavelength-sensing modules for particularly required bands.
{"title":"A wavelength sensor using a structure of curved optical waveguide","authors":"K. Sae-tang, S. Somkuarnpanit, S. Khuntaweetep","doi":"10.1109/COMMAD.2002.1237235","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237235","url":null,"abstract":"This paper proposes a wavelength sensor using a section of curved optical waveguide. The finite-difference time-domain (FDTD) method is used in analysis of the field intensity of light propagating thorough the structure. Light with different wavelengths would propagate in different energy transmission, which allows to the technique to indicate the light wavelength. Parameters of the structure such as: w, T and R are appropriately considered. The device with a width of 0.6 /spl mu/m and thickness of 0.6 /spl mu/m provides the maximum light transmission. At the particular curve radius of 3 /spl mu/m, the structure could be employed to measure the communication wavelengths, in this case in a range between 1520 and 1580 nm, with a correlation factor of 99.82%. The wide band of wavelengths could possibly be carried out using a number of wavelength-sensing modules for particularly required bands.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125502431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237222
J. Hugmann, B. S. Richards, A. Crosky
It is possible to tune the refractive index (n) of a TiO/sub 2/ film to the optimum value for an encapsulated silicon solar cell by annealing the coating after deposition. Annealing causes a change in the volume fraction of rutile and this was examined as a function of annealing temperature for thin (/spl sim/70 nm) TiO/sub 2/ films on a silicon substrate using micro-Raman spectroscopy and glancing angle X-ray diffraction. Both techniques were able to monitor the progression of the phase change in the films. Micro-Raman spectroscopy provided a rapid means to monitor the phase change and could detect phase fractions below approximately 5%. Glancing angle X-ray diffraction provided quantitative results but the technique was considerably more time consuming. The results indicated that the refractive index varied linearly with the rutile phase fraction.
{"title":"Phase characterisation of TiO/sub 2/ thin films using micro-Raman spectroscopy and glancing angle X-ray diffraction","authors":"J. Hugmann, B. S. Richards, A. Crosky","doi":"10.1109/COMMAD.2002.1237222","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237222","url":null,"abstract":"It is possible to tune the refractive index (n) of a TiO/sub 2/ film to the optimum value for an encapsulated silicon solar cell by annealing the coating after deposition. Annealing causes a change in the volume fraction of rutile and this was examined as a function of annealing temperature for thin (/spl sim/70 nm) TiO/sub 2/ films on a silicon substrate using micro-Raman spectroscopy and glancing angle X-ray diffraction. Both techniques were able to monitor the progression of the phase change in the films. Micro-Raman spectroscopy provided a rapid means to monitor the phase change and could detect phase fractions below approximately 5%. Glancing angle X-ray diffraction provided quantitative results but the technique was considerably more time consuming. The results indicated that the refractive index varied linearly with the rutile phase fraction.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126086184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237279
V. Ligatchev, T. Wong, Rusli
Carbon-doped hydrogenated silicon oxide (SiOCH) low-k films have been prepared using 13.56 MHz discharge in trimethylsilane (3MS) - oxygen gas mixtures at 3, 4, and 5 Torr sustained with RF power densities 1.3 - 2.6 W/cm/sup 2/. The atomic structure of the SiOCH films appears to be a mixture of the amorphous SiO/sub 2/-like and the partially polycrystalline SiC-like phases. Results of the infrared spectroscopy and atomic force microscopy reflect the increment in the volume fraction of the SiC-like phase from 0.22 - 0.28 to 0.36 - 0.39 as the RF power increment. Steady-state near-UV laser-excited (364 nm wavelength, 40/spl plusmn/2 mW) photoluminescence (PL) has been studied at room temperatures in the visible ( 1.8 eV - 3.1 eV) range of photon energies. Two main bands of the PL signal (at the photon energies of 2.5 - 2.6 eV and 2.8 2.9 eV) are observed. Intensities of the both bands are changed non-monotonically with RF power, whereas the bandwidth of /spl sim/0.1 eV remains almost invariable. It is likely that the above lines are originated by the radiative recombination involving D/sub 1/ centres in the crystalline SiC-like phases. Explanation of the PL intensity dependence on the RF power density can be based on results of studies of morphology of the SiOCH films.
{"title":"A photoluminescence of low-K SiOCH films, prepared by PECVD","authors":"V. Ligatchev, T. Wong, Rusli","doi":"10.1109/COMMAD.2002.1237279","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237279","url":null,"abstract":"Carbon-doped hydrogenated silicon oxide (SiOCH) low-k films have been prepared using 13.56 MHz discharge in trimethylsilane (3MS) - oxygen gas mixtures at 3, 4, and 5 Torr sustained with RF power densities 1.3 - 2.6 W/cm/sup 2/. The atomic structure of the SiOCH films appears to be a mixture of the amorphous SiO/sub 2/-like and the partially polycrystalline SiC-like phases. Results of the infrared spectroscopy and atomic force microscopy reflect the increment in the volume fraction of the SiC-like phase from 0.22 - 0.28 to 0.36 - 0.39 as the RF power increment. Steady-state near-UV laser-excited (364 nm wavelength, 40/spl plusmn/2 mW) photoluminescence (PL) has been studied at room temperatures in the visible ( 1.8 eV - 3.1 eV) range of photon energies. Two main bands of the PL signal (at the photon energies of 2.5 - 2.6 eV and 2.8 2.9 eV) are observed. Intensities of the both bands are changed non-monotonically with RF power, whereas the bandwidth of /spl sim/0.1 eV remains almost invariable. It is likely that the above lines are originated by the radiative recombination involving D/sub 1/ centres in the crystalline SiC-like phases. Explanation of the PL intensity dependence on the RF power density can be based on results of studies of morphology of the SiOCH films.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115978606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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