Quantum dots (QDs) have the advantages of spectrally adjustable, high quantum yield and narrow half-peak width, and are the most potential light-converting materials for white light that achieve high color rendering index and high saturation. The InGaN blue light chip currently used excites Ce-doped yttrium aluminum garnet (YAG: Ce3+) yellow phosphor, and the white light-emitting diode (WLED) realized exhibits color rendering index (CRI) <80 and an unsatisfactory color coordinate because of lack of red spectral components. In order to improve the CRI of white LEDs, in this paper, we fabricated InP / ZnS green-emitting QDs and InP / ZnSe / ZnS red-emitting QDs, and excited YAG: Ce3+ yellow phosphor, InP / ZnS green-emitting QDs and InP / ZnSe / ZnS redemitting QDs with blue chip , made WLED (I), and compared with WLED (II) generated by using blue LED chip to excite YAG: Ce3+ yellow phosphor. The result shows that the WLED (I) achieves a CRI of 90.3 at a driving current of 5 mA. The Commission International de L’Eclairage (CIE) chromaticity coordinates are (0.3393, 0.3342), and the correlated color temperature (CCT) is 5186K, which is high quality white light close to sunlight.
{"title":"High color rendering index white LEDs fabricated using InP/ZnS green-emitting quantum dots and InP/ZnSe/ZnS red-emitting quantum dots","authors":"Doudou Zhang, Yuxian Yan, Fan Cao, Gongli Lin, Xuyong Yang, Wanwan Li, Luqiao Yin, Jianhua Zhang","doi":"10.1109/SSLChinaIFWS49075.2019.9019770","DOIUrl":"https://doi.org/10.1109/SSLChinaIFWS49075.2019.9019770","url":null,"abstract":"Quantum dots (QDs) have the advantages of spectrally adjustable, high quantum yield and narrow half-peak width, and are the most potential light-converting materials for white light that achieve high color rendering index and high saturation. The InGaN blue light chip currently used excites Ce-doped yttrium aluminum garnet (YAG: Ce3+) yellow phosphor, and the white light-emitting diode (WLED) realized exhibits color rendering index (CRI) <80 and an unsatisfactory color coordinate because of lack of red spectral components. In order to improve the CRI of white LEDs, in this paper, we fabricated InP / ZnS green-emitting QDs and InP / ZnSe / ZnS red-emitting QDs, and excited YAG: Ce3+ yellow phosphor, InP / ZnS green-emitting QDs and InP / ZnSe / ZnS redemitting QDs with blue chip , made WLED (I), and compared with WLED (II) generated by using blue LED chip to excite YAG: Ce3+ yellow phosphor. The result shows that the WLED (I) achieves a CRI of 90.3 at a driving current of 5 mA. The Commission International de L’Eclairage (CIE) chromaticity coordinates are (0.3393, 0.3342), and the correlated color temperature (CCT) is 5186K, which is high quality white light close to sunlight.","PeriodicalId":315846,"journal":{"name":"2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)","volume":"482 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122755662","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 : 2019-11-01DOI: 10.1109/SSLChinaIFWS49075.2019.9019800
Mingle Liao, Wuze Xie, Zejia Deng, Junze Li
GaN-based short wavelength laser diode is a promising lasing source for a variety of applications in the visible light spectrum. In this work, we report on a wavelength stabilized blue laser utilizing distributed bragg reflector (DBR) based on InGaN/GaN. The passive DBR is located on the rear side of the ridge waveguide, acting as a high-reflective reflector to the cavity. The uniform grating structure has a period of 1.55μm, duty ratio of 75% and etched depth of 500nm, and is defined by electron-beam lithography (EBL) and etched by Inductively Coupled Plasma (ICP). The electrical and optical characterizes of 19th order DBR laser emitting at a wavelength of 403nm are measured under the pulse drive condition to avoid thermal accumulation in the diode. A minimum emission linewidth of 0.45nm is observed, indicating the mode selection function is realized by the DBR. High wavelength stabilization with driving currents can be obtained due to the separation of active area and grating region in DBR laser. Experiment results also show that temperature stable emission with a wavelength shift of 0.013 nm/K is obtained within the DBR laser.
{"title":"A Wavelength Stabilized GaN based Laser Utilizing Distributed Bragg Reflector","authors":"Mingle Liao, Wuze Xie, Zejia Deng, Junze Li","doi":"10.1109/SSLChinaIFWS49075.2019.9019800","DOIUrl":"https://doi.org/10.1109/SSLChinaIFWS49075.2019.9019800","url":null,"abstract":"GaN-based short wavelength laser diode is a promising lasing source for a variety of applications in the visible light spectrum. In this work, we report on a wavelength stabilized blue laser utilizing distributed bragg reflector (DBR) based on InGaN/GaN. The passive DBR is located on the rear side of the ridge waveguide, acting as a high-reflective reflector to the cavity. The uniform grating structure has a period of 1.55μm, duty ratio of 75% and etched depth of 500nm, and is defined by electron-beam lithography (EBL) and etched by Inductively Coupled Plasma (ICP). The electrical and optical characterizes of 19th order DBR laser emitting at a wavelength of 403nm are measured under the pulse drive condition to avoid thermal accumulation in the diode. A minimum emission linewidth of 0.45nm is observed, indicating the mode selection function is realized by the DBR. High wavelength stabilization with driving currents can be obtained due to the separation of active area and grating region in DBR laser. Experiment results also show that temperature stable emission with a wavelength shift of 0.013 nm/K is obtained within the DBR laser.","PeriodicalId":315846,"journal":{"name":"2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114603694","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 : 2019-11-01DOI: 10.1109/SSLChinaIFWS49075.2019.9019756
Xiaojie Zhao, Mengxin Li, Yandan Lin, W. Xu
There have been many studies on stroboscopic effect from LEDs, which is considered unacceptable to affect psychological cognition. As a new measurement, Stroboscopic Effect Visibility Measure (SVM), can quantify the visibility of stroboscopic effect in general lighting applications. However, the relationship, if any, between SVM and human cognitive performance has not been specifically elucidated, such as spatial environment and work performance. Therefore, under six SVM values representing different lighting environments, through the D2 task, the rotating disk and the Landolt ring task, objects can perceive the stroboscopic effect in lighting environment, and use scales to make the self-cognitive judgement of spatial environment and work performance. The experimental results show that there is a significant relationship between the visibility of stroboscopic effect and cognitive performance. Subjects reported flicker, discrete spatial motion and bad environment perception in response to the higher visibility of stroboscopic effect. In addition, the visibility of stroboscopic effect also may have a significant impact on physiological indicators, subjects are more nervous during the D2 task, meanwhile the vision and attention are all decreased with a high SVM during the rotating disk.
{"title":"Study of the Stroboscopic Effect Visibility Measure (SVM) based on Cognitive Performance","authors":"Xiaojie Zhao, Mengxin Li, Yandan Lin, W. Xu","doi":"10.1109/SSLChinaIFWS49075.2019.9019756","DOIUrl":"https://doi.org/10.1109/SSLChinaIFWS49075.2019.9019756","url":null,"abstract":"There have been many studies on stroboscopic effect from LEDs, which is considered unacceptable to affect psychological cognition. As a new measurement, Stroboscopic Effect Visibility Measure (SVM), can quantify the visibility of stroboscopic effect in general lighting applications. However, the relationship, if any, between SVM and human cognitive performance has not been specifically elucidated, such as spatial environment and work performance. Therefore, under six SVM values representing different lighting environments, through the D2 task, the rotating disk and the Landolt ring task, objects can perceive the stroboscopic effect in lighting environment, and use scales to make the self-cognitive judgement of spatial environment and work performance. The experimental results show that there is a significant relationship between the visibility of stroboscopic effect and cognitive performance. Subjects reported flicker, discrete spatial motion and bad environment perception in response to the higher visibility of stroboscopic effect. In addition, the visibility of stroboscopic effect also may have a significant impact on physiological indicators, subjects are more nervous during the D2 task, meanwhile the vision and attention are all decreased with a high SVM during the rotating disk.","PeriodicalId":315846,"journal":{"name":"2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121274577","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 : 2019-11-01DOI: 10.1109/SSLChinaIFWS49075.2019.9019769
Zhizhong Chen, Shiwei Feng, Guoyi Zhang, B. Shen, Chengcheng Li, F. Jiao, J. Zhan, Yifan Chen, Yiyong Chen, J. Nie, T. Zhao, X. Kang
In this work, different sizes of micro-light-emitting diodes (μLEDs) were fabricated on the sapphire and GaN substrates. The thermal characteristics of μLEDs were studied by the forward voltage method, thermal transient measurement, and infrared (IR) thermal imaging. The μLEDs on the GaN substrate showed an approximately 10°C lower junction temperature and smaller amplitude of the K factors than those on the sapphire substrate under the current injection level of 4 kA/cm2. IR thermal imaging results showed the uniform temperature distributed on the GaN substrate. The thermal transient measurement showed that the thermal resistances of the mesa, epilayer, and the interface of GaN/substrate were reduced significantly for μLEDs on the GaN substrate. This means that a high-quality GaN crystal and homogeneous interface corresponded to little scattering for phonons. The APSYS simulation indicated that the high thermal and electrical conductivity of the GaN substrate played a key role in the low junction temperature and uniform temperature distribution. A small-sized μLED combined with a GaN substrate can become a perfect candidate for high-power applications and visible light communication.
{"title":"Study on 3D thermal transport in micro-LEDs on GaN substrate at the level of kW/cm2","authors":"Zhizhong Chen, Shiwei Feng, Guoyi Zhang, B. Shen, Chengcheng Li, F. Jiao, J. Zhan, Yifan Chen, Yiyong Chen, J. Nie, T. Zhao, X. Kang","doi":"10.1109/SSLChinaIFWS49075.2019.9019769","DOIUrl":"https://doi.org/10.1109/SSLChinaIFWS49075.2019.9019769","url":null,"abstract":"In this work, different sizes of micro-light-emitting diodes (μLEDs) were fabricated on the sapphire and GaN substrates. The thermal characteristics of μLEDs were studied by the forward voltage method, thermal transient measurement, and infrared (IR) thermal imaging. The μLEDs on the GaN substrate showed an approximately 10°C lower junction temperature and smaller amplitude of the K factors than those on the sapphire substrate under the current injection level of 4 kA/cm2. IR thermal imaging results showed the uniform temperature distributed on the GaN substrate. The thermal transient measurement showed that the thermal resistances of the mesa, epilayer, and the interface of GaN/substrate were reduced significantly for μLEDs on the GaN substrate. This means that a high-quality GaN crystal and homogeneous interface corresponded to little scattering for phonons. The APSYS simulation indicated that the high thermal and electrical conductivity of the GaN substrate played a key role in the low junction temperature and uniform temperature distribution. A small-sized μLED combined with a GaN substrate can become a perfect candidate for high-power applications and visible light communication.","PeriodicalId":315846,"journal":{"name":"2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133792139","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 : 2019-11-01DOI: 10.1109/SSLChinaIFWS49075.2019.9019814
F. Keil, K. Hofmann
This work presents a comparative study between a set of high-end, name-brand LED off-line drivers and a second set of low-cost drivers. To determine the lifetime of the devices in each sample an accelerated lifetime test was used. The degradation of important parameters of the devices during the test, as well as their lifetime, were recorded. A failure analysis reveals two important failure causes: galvanic corrosion and failed metallized film capacitors. Galvanic corrosion is found to be more frequent in the sample of low-cost devices. It is proposed that this is due to lack of proper cleaning of the assembled circuit board. Finally, the question whether the high-end sample has a significantly longer lifetime compared to the low-cost sample is assessed through a proper statistical test. A higher mean lifetime for the high-end sample cannot be confirmed.
{"title":"A Comparative Study of the Lifetimes of High-End and Low-Cost Off-Line LED Drivers Under Accelerated Test Conditions","authors":"F. Keil, K. Hofmann","doi":"10.1109/SSLChinaIFWS49075.2019.9019814","DOIUrl":"https://doi.org/10.1109/SSLChinaIFWS49075.2019.9019814","url":null,"abstract":"This work presents a comparative study between a set of high-end, name-brand LED off-line drivers and a second set of low-cost drivers. To determine the lifetime of the devices in each sample an accelerated lifetime test was used. The degradation of important parameters of the devices during the test, as well as their lifetime, were recorded. A failure analysis reveals two important failure causes: galvanic corrosion and failed metallized film capacitors. Galvanic corrosion is found to be more frequent in the sample of low-cost devices. It is proposed that this is due to lack of proper cleaning of the assembled circuit board. Finally, the question whether the high-end sample has a significantly longer lifetime compared to the low-cost sample is assessed through a proper statistical test. A higher mean lifetime for the high-end sample cannot be confirmed.","PeriodicalId":315846,"journal":{"name":"2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117292311","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 : 2019-11-01DOI: 10.1109/SSLChinaIFWS49075.2019.9019789
Tianfeng Wang, Jianfei Dong, Guoqi Zhang
Microbial infection is one of the most common diseases in the world, which gives rise to morbidity and mortality. At present, the main treatment is using antibiotic drugs. However, the side effects range from fever and nausea to major allergic reactions cannot be ignored. Moreover, the increasing drug resistance also necessitates a new safe alternative therapeutic approach against the microbial infections. As non-antibiotic methods, photodynamic therapies (PDT) and anti-microbial blue light (ABL) therapies have been investigated in this field. However, one challenge of the PDT is the introduction of photosensitizers to the specific pathogens rather than the host cells. In contrast, ABL therapies inactivate the microbes without the involvement of exogenous photosensitizers. The general mechanism of ABL therapies is that ABL can excite the endogenous photosensitizers, and trigger the accumulation of cytotoxic reactive oxygen species (ROS), which in turn leads to cell damage. In this study, we investigated the inhibitive capability of the 405nm LED light source on Candida albicans (C. albicans). C. albicans is the most common pathogen of fungal infections. The intracellular ROS level of C. albicans was detected after the ABL irradiation. The results obtained from this study demonstrated that irradiation of 405nm LED significantly inactivated the C. albicans. The viability of C. albicans was reduced to 1% after 25 minutes of ABL exposure of 50mW/cm2. On the other hand, the intracellular ROS was increased by the ABL irradiation. This study demonstrates the effectiveness of applying 405nm LED to threat the infection caused by C. albicans, as the result of the stimulated accumulation of the intracellular cytotoxic ROS by this light.
{"title":"Applying LEDs as Therapeutic Light Sources for Anti-microbial Treatment: An Experimental Study","authors":"Tianfeng Wang, Jianfei Dong, Guoqi Zhang","doi":"10.1109/SSLChinaIFWS49075.2019.9019789","DOIUrl":"https://doi.org/10.1109/SSLChinaIFWS49075.2019.9019789","url":null,"abstract":"Microbial infection is one of the most common diseases in the world, which gives rise to morbidity and mortality. At present, the main treatment is using antibiotic drugs. However, the side effects range from fever and nausea to major allergic reactions cannot be ignored. Moreover, the increasing drug resistance also necessitates a new safe alternative therapeutic approach against the microbial infections. As non-antibiotic methods, photodynamic therapies (PDT) and anti-microbial blue light (ABL) therapies have been investigated in this field. However, one challenge of the PDT is the introduction of photosensitizers to the specific pathogens rather than the host cells. In contrast, ABL therapies inactivate the microbes without the involvement of exogenous photosensitizers. The general mechanism of ABL therapies is that ABL can excite the endogenous photosensitizers, and trigger the accumulation of cytotoxic reactive oxygen species (ROS), which in turn leads to cell damage. In this study, we investigated the inhibitive capability of the 405nm LED light source on Candida albicans (C. albicans). C. albicans is the most common pathogen of fungal infections. The intracellular ROS level of C. albicans was detected after the ABL irradiation. The results obtained from this study demonstrated that irradiation of 405nm LED significantly inactivated the C. albicans. The viability of C. albicans was reduced to 1% after 25 minutes of ABL exposure of 50mW/cm2. On the other hand, the intracellular ROS was increased by the ABL irradiation. This study demonstrates the effectiveness of applying 405nm LED to threat the infection caused by C. albicans, as the result of the stimulated accumulation of the intracellular cytotoxic ROS by this light.","PeriodicalId":315846,"journal":{"name":"2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131098035","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 : 2019-11-01DOI: 10.1109/SSLChinaIFWS49075.2019.9019802
Yudi Wang, L. Xia, Jinfeng Huang, R. Xu, Xiaofeng Liu
The appearance of objects varies enormously depending on light diffuseness. Conversely, the appearance of objects might be a cue to the light diffuseness. This would provide a solution for lighting designers to guess-estimate the light diffuseness levels based on the appearance of a light probe. However, the question remains whether rough probe provides additional cues about light diffuseness comparing with the smooth probes. If the answer to the last question is yes, whether different kinds of roughness performs the same. Furthermore, how the estimation of light diffuseness might be influenced by the illumination directions. To answer these questions, an appearance-matching experiment was performed, within which white spherical probes with four kinds of surface mesoreliefs were adopted and 5 illumination directions were tested. The results confirmed that observers’ abilities to match the light diffuseness were improved by the use of probes with 3D texture, which means that observers can derive light diffuseness from the additional cues provided by the texture over the rough probe. However, the results showed that the roughness has no obvious effect on diffuseness perception at illumination direction of 90° or 120° owing to the much useful information provided by the terminator of the body shadow.
{"title":"Infer light diffuseness on light probes with different kinds of mesoreliefs","authors":"Yudi Wang, L. Xia, Jinfeng Huang, R. Xu, Xiaofeng Liu","doi":"10.1109/SSLChinaIFWS49075.2019.9019802","DOIUrl":"https://doi.org/10.1109/SSLChinaIFWS49075.2019.9019802","url":null,"abstract":"The appearance of objects varies enormously depending on light diffuseness. Conversely, the appearance of objects might be a cue to the light diffuseness. This would provide a solution for lighting designers to guess-estimate the light diffuseness levels based on the appearance of a light probe. However, the question remains whether rough probe provides additional cues about light diffuseness comparing with the smooth probes. If the answer to the last question is yes, whether different kinds of roughness performs the same. Furthermore, how the estimation of light diffuseness might be influenced by the illumination directions. To answer these questions, an appearance-matching experiment was performed, within which white spherical probes with four kinds of surface mesoreliefs were adopted and 5 illumination directions were tested. The results confirmed that observers’ abilities to match the light diffuseness were improved by the use of probes with 3D texture, which means that observers can derive light diffuseness from the additional cues provided by the texture over the rough probe. However, the results showed that the roughness has no obvious effect on diffuseness perception at illumination direction of 90° or 120° owing to the much useful information provided by the terminator of the body shadow.","PeriodicalId":315846,"journal":{"name":"2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125552660","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}
In this work, we develop an optimized VDMOSFET cell structure based on 4H-SiC material. In the optimized structure, two high n-doped regions are added at both sides of the JFET region. Simulation results reveal that the additional n-doped regions not only effectively limit the depletion width in JFET region at ON-state, but also could protect the oxide layer at OFF-state due to depletion expansion. As a result, the optimized structure reduces the specific ON-resistance by 18% while keeping breakdown voltage as roughly high as the conventional structure; meanwhile, the value of figure of merit increases by 22%, which exhibits a significant improvement in device performance.
{"title":"Optimized Design of 4H-SiC VDMOSFET for Low ON-resistance","authors":"Defu Yin, Zhiming Wu, Xian Zou, Yongqiang Sun, Yaping Wu, Weiping Wang, Xu Li, Junyong Kang","doi":"10.1109/SSLChinaIFWS49075.2019.9019763","DOIUrl":"https://doi.org/10.1109/SSLChinaIFWS49075.2019.9019763","url":null,"abstract":"In this work, we develop an optimized VDMOSFET cell structure based on 4H-SiC material. In the optimized structure, two high n-doped regions are added at both sides of the JFET region. Simulation results reveal that the additional n-doped regions not only effectively limit the depletion width in JFET region at ON-state, but also could protect the oxide layer at OFF-state due to depletion expansion. As a result, the optimized structure reduces the specific ON-resistance by 18% while keeping breakdown voltage as roughly high as the conventional structure; meanwhile, the value of figure of merit increases by 22%, which exhibits a significant improvement in device performance.","PeriodicalId":315846,"journal":{"name":"2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116597197","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 : 2019-11-01DOI: 10.1109/SSLChinaIFWS49075.2019.9019751
Hung-Wei Chen, Chien-Yu Chen, Pei-Jung Wu
The mainly of the physiological measurement mode is measuring EEG and HRV, as an indicator to explore the impact on subject’s non-subjective of the lighting, and using psychological questionnaires as subjective evaluation of the subject’s physiological effects.The main purpose of this research is to look for a tunable intelligent light suitable for sleep. Subjects were a total of 30 (14 male and 16 female), mean age 23.83±0.86 years old. All subjects were required to subject to no light sleep, Good-night light sleep, and low-color-temperature light sleep. Their EEG and ECG are detected during the whole processing. Then through the analysis of HRV and EEG, observed the subject’s quality of sleep. Experimental results of Good-night light is the subject’s sleep for the δ wave impact of the significant rise. HRV part, nHFP strength portion are higher than no light sleep and low-color-temperature lighting sleep. This proved Good-night light really help to improve the quality of sleep.
{"title":"The Influence of Lighting on Human Circadian Rhythms","authors":"Hung-Wei Chen, Chien-Yu Chen, Pei-Jung Wu","doi":"10.1109/SSLChinaIFWS49075.2019.9019751","DOIUrl":"https://doi.org/10.1109/SSLChinaIFWS49075.2019.9019751","url":null,"abstract":"The mainly of the physiological measurement mode is measuring EEG and HRV, as an indicator to explore the impact on subject’s non-subjective of the lighting, and using psychological questionnaires as subjective evaluation of the subject’s physiological effects.The main purpose of this research is to look for a tunable intelligent light suitable for sleep. Subjects were a total of 30 (14 male and 16 female), mean age 23.83±0.86 years old. All subjects were required to subject to no light sleep, Good-night light sleep, and low-color-temperature light sleep. Their EEG and ECG are detected during the whole processing. Then through the analysis of HRV and EEG, observed the subject’s quality of sleep. Experimental results of Good-night light is the subject’s sleep for the δ wave impact of the significant rise. HRV part, nHFP strength portion are higher than no light sleep and low-color-temperature lighting sleep. This proved Good-night light really help to improve the quality of sleep.","PeriodicalId":315846,"journal":{"name":"2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116853395","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 : 2019-11-01DOI: 10.1109/SSLChinaIFWS49075.2019.9019773
Y. Liang, Chong-yu Shen, Junfei Chen, Weiye Zheng, Zheng Xu, J. G. Liu
The operating lifetime of quantum-dot light-emitting diodes (QLEDs) is a critical parameter for quantum-dot display which is becoming an emerging display technology. To pinpoint the causes of device degradation, we demonstrated an enhanced reliability of all-solution processed QLEDs by introducing an insulating interfacial layer between the ETL and the QDs. It is confirmed that a PMMA interfacial layer can delay the electron transfer and reduce the nonradiative recombination, which in turn slow down the degradation of QDs-ZnO layer. In comparison with the standard QLEDs, device fabricated with PMMA of 1.0 mg/ml shows longest lifetime of 28.7h, which improves the lifetime by 50%. We studied the effect of electrons transfer on the degradation mechanisms, which lays the foundation for further improvement of the device life.
{"title":"Influence of the Charge Transfer on the Lifetime of Quantum-Dot Light-Emitting Diodes","authors":"Y. Liang, Chong-yu Shen, Junfei Chen, Weiye Zheng, Zheng Xu, J. G. Liu","doi":"10.1109/SSLChinaIFWS49075.2019.9019773","DOIUrl":"https://doi.org/10.1109/SSLChinaIFWS49075.2019.9019773","url":null,"abstract":"The operating lifetime of quantum-dot light-emitting diodes (QLEDs) is a critical parameter for quantum-dot display which is becoming an emerging display technology. To pinpoint the causes of device degradation, we demonstrated an enhanced reliability of all-solution processed QLEDs by introducing an insulating interfacial layer between the ETL and the QDs. It is confirmed that a PMMA interfacial layer can delay the electron transfer and reduce the nonradiative recombination, which in turn slow down the degradation of QDs-ZnO layer. In comparison with the standard QLEDs, device fabricated with PMMA of 1.0 mg/ml shows longest lifetime of 28.7h, which improves the lifetime by 50%. We studied the effect of electrons transfer on the degradation mechanisms, which lays the foundation for further improvement of the device life.","PeriodicalId":315846,"journal":{"name":"2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115880960","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：