We investigate the mechanism for the improvement of p-type doping efficiency in Mg-Al0.14Ga0.86N/GaN super- lattices （SLs）. It is shown that the hole concentration of SLs increases by nearly an order of magnitude, f...We investigate the mechanism for the improvement of p-type doping efficiency in Mg-Al0.14Ga0.86N/GaN super- lattices （SLs）. It is shown that the hole concentration of SLs increases by nearly an order of magnitude, from 1.1 × 1017 to 9.3×1017 cm-3, when an AlN interlayer is inserted to modulate the strains. SchrSdinger-Poisson self-consistent calculations suggest that such an increase could be attributed to the reduction of donor-like defects caused by the strain modulation induced by the AlN interlayer. Additionally, the donor-acceptor pair emission exhibits a remarkable decrease in intensity of the cathodoluminescence spectrumlfor SLs with an A1N interlayer. This supports the theoretical calculations and indicates that the strain modulation of SLs could be beneficial to the donor-like defect suppression as well as the p-type doping efficiency improvement.展开更多
The InGaN/GaN blue light emitting diode（LED） is numerically investigated using a triangular-shaped quantum well model,which involves analysis on its energy band,carrier concentration,overlap of electron and hole wav...The InGaN/GaN blue light emitting diode（LED） is numerically investigated using a triangular-shaped quantum well model,which involves analysis on its energy band,carrier concentration,overlap of electron and hole wave functions,radiative recombination rate,and internal quantum efficiency.The simulation results reveal that the InGaN/GaN blue light emitting diode with triangular quantum wells exhibits a higher radiative recombination rate than the conventional light emitting diode with rectangular quantum wells due to the enhanced overlap of electron and hole wave functions（above 90%） under the polarization field.Consequently,the efficiency droop is only 18% in the light emitting diode with triangular-shaped quantum wells,which is three times lower than that in a conventional LED.展开更多
We theoretically investigate the optical properties of an ultra-thin InN layer embedded in InGaN matrix for light emitters. The peak emission wavelength extends from ultraviolet （374 nm） to green （536 nm） with InN...We theoretically investigate the optical properties of an ultra-thin InN layer embedded in InGaN matrix for light emitters. The peak emission wavelength extends from ultraviolet （374 nm） to green （536 nm） with InN quantum well thickness increasing from 1 monolayer to 2 monolayers, while the overlap of electron–hole wave function remains at a high level （larger than 90%）. Increase of In content in InGaN matrix provides a better approach to longer wavelength emission, which only reduces the spontaneous emission rate slightly compared with the case of increasing In content of the conventional InGaN quantum well. Also, the transparency carrier density derived from gain spectrum is of the same order as that in the conventional blue laser diode. Our study provides skillful design on the development of novel structure InN-based light emitting diodes as well as laser diodes.展开更多
The influence of the width of a lattice-matched A10.82In0.18N/GaN single quantum well （SQW） on the absorption coefficients and wavelength of the intersubband transition （ISBT） has been investigated by solving the ...The influence of the width of a lattice-matched A10.82In0.18N/GaN single quantum well （SQW） on the absorption coefficients and wavelength of the intersubband transition （ISBT） has been investigated by solving the Schr5dinger and Poisson equations self-consistently. The wavelength of 1-2 ISBT increases with L, the thickness of the single quantum well, ranging from 2.88 ~m to 3.59 ~.m. The absorption coefficients of 1-2 ISBT increase with L at first and then decrease with L, with a maximum when L is equal to 2.6 nm. The wavelength of 1-3 ISBT decreases with L at first and then increases with L, with a minimum when L is equal to 4 nm, ranging from approximately 2.03 p^m to near 2.11 p.m. The absorption coefficients of 1-3 ISBT decrease with L. The results indicate that mid-infrared can be realized by the A10.s2In0.1sN/GaN SQW. In addition, the wavelength and absorption coefficients of ISBT can be adjusted by changing the width of the SQW.展开更多
Visible light communication(VLC)technology is a new type of wireless communication technology,which employs a light source as the carrier of information to realize illumination and communication simultaneously.This pa...Visible light communication(VLC)technology is a new type of wireless communication technology,which employs a light source as the carrier of information to realize illumination and communication simultaneously.This paper adopts a single In Ga N/Ga N-base multi-quantum well blue micro-light emitting diode(LED)as the light source,designs pre-emphasis circuit,LED driver circuit,impedance matching network,etc.,and builds a high-speed real-time VLC system.It has been verified that the LED achieves a 3 d B modulation bandwidth of 450 MHz or more;and the real-time communication rate reaches over 800 Mbit/s at a distance of 2 m.The communication bit error rate(BER)is as low as 3.02×10^(-12)at a communication rate of 622 Mbit/s.Experimental indicators including 3 d B bandwidth,communication rate,and communication BER are all taken into account.Therefore,this VLC system supports high-quality high-speed real-time communication.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61076012,61076013,and 51102003)the National High Technology Research and Development Program of China (Grant No. 2007AA03Z403)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education,China (Grant No. 20100001120014)the National Basic Research Program of China (Grant No. 2012CB619304)
文摘We investigate the mechanism for the improvement of p-type doping efficiency in Mg-Al0.14Ga0.86N/GaN super- lattices （SLs）. It is shown that the hole concentration of SLs increases by nearly an order of magnitude, from 1.1 × 1017 to 9.3×1017 cm-3, when an AlN interlayer is inserted to modulate the strains. SchrSdinger-Poisson self-consistent calculations suggest that such an increase could be attributed to the reduction of donor-like defects caused by the strain modulation induced by the AlN interlayer. Additionally, the donor-acceptor pair emission exhibits a remarkable decrease in intensity of the cathodoluminescence spectrumlfor SLs with an A1N interlayer. This supports the theoretical calculations and indicates that the strain modulation of SLs could be beneficial to the donor-like defect suppression as well as the p-type doping efficiency improvement.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61076013,51102003,and 60990313)the National Basic Research Program of China (Grant No. 2012CB619304)the Specialized Research Fund for the Doctoral Program of Higher Education,China (Grant No. 20100001120014)
文摘The InGaN/GaN blue light emitting diode（LED） is numerically investigated using a triangular-shaped quantum well model,which involves analysis on its energy band,carrier concentration,overlap of electron and hole wave functions,radiative recombination rate,and internal quantum efficiency.The simulation results reveal that the InGaN/GaN blue light emitting diode with triangular quantum wells exhibits a higher radiative recombination rate than the conventional light emitting diode with rectangular quantum wells due to the enhanced overlap of electron and hole wave functions（above 90%） under the polarization field.Consequently,the efficiency droop is only 18% in the light emitting diode with triangular-shaped quantum wells,which is three times lower than that in a conventional LED.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61076013, 51272008, and 51102003)the National Basic Research Program of China (Grant No. 2012CB619304)+1 种基金the Beijing Municipal Science & Technology Commission (Grant No. D111100001711002)the Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant No. 20100001120014)
文摘We theoretically investigate the optical properties of an ultra-thin InN layer embedded in InGaN matrix for light emitters. The peak emission wavelength extends from ultraviolet （374 nm） to green （536 nm） with InN quantum well thickness increasing from 1 monolayer to 2 monolayers, while the overlap of electron–hole wave function remains at a high level （larger than 90%）. Increase of In content in InGaN matrix provides a better approach to longer wavelength emission, which only reduces the spontaneous emission rate slightly compared with the case of increasing In content of the conventional InGaN quantum well. Also, the transparency carrier density derived from gain spectrum is of the same order as that in the conventional blue laser diode. Our study provides skillful design on the development of novel structure InN-based light emitting diodes as well as laser diodes.
基金Project supported by the National High Technology Research and Development Program of China (Grant No.2007AA03Z403)the National Natural Science Foundation of China (Grant Nos.61076013 and 60776042)the National Basic Research Program of China (Grant No.2006CB921607)
文摘The influence of the width of a lattice-matched A10.82In0.18N/GaN single quantum well （SQW） on the absorption coefficients and wavelength of the intersubband transition （ISBT） has been investigated by solving the Schr5dinger and Poisson equations self-consistently. The wavelength of 1-2 ISBT increases with L, the thickness of the single quantum well, ranging from 2.88 ~m to 3.59 ~.m. The absorption coefficients of 1-2 ISBT increase with L at first and then decrease with L, with a maximum when L is equal to 2.6 nm. The wavelength of 1-3 ISBT decreases with L at first and then increases with L, with a minimum when L is equal to 4 nm, ranging from approximately 2.03 p^m to near 2.11 p.m. The absorption coefficients of 1-3 ISBT decrease with L. The results indicate that mid-infrared can be realized by the A10.s2In0.1sN/GaN SQW. In addition, the wavelength and absorption coefficients of ISBT can be adjusted by changing the width of the SQW.
基金supported by the Science of Technology Program of Guangdong Province(No.2015B010110002)the Science Technology Program of Guangzhou(No.201804010166)
文摘Visible light communication(VLC)technology is a new type of wireless communication technology,which employs a light source as the carrier of information to realize illumination and communication simultaneously.This paper adopts a single In Ga N/Ga N-base multi-quantum well blue micro-light emitting diode(LED)as the light source,designs pre-emphasis circuit,LED driver circuit,impedance matching network,etc.,and builds a high-speed real-time VLC system.It has been verified that the LED achieves a 3 d B modulation bandwidth of 450 MHz or more;and the real-time communication rate reaches over 800 Mbit/s at a distance of 2 m.The communication bit error rate(BER)is as low as 3.02×10^(-12)at a communication rate of 622 Mbit/s.Experimental indicators including 3 d B bandwidth,communication rate,and communication BER are all taken into account.Therefore,this VLC system supports high-quality high-speed real-time communication.
