Magnetotransport properties of two-dimensional electron gases （2DEG） in AlxGa1-x N/GaN heterostructures with different Al compositions are investigated by magnetotransport measurements at low temperatures and in hig...Magnetotransport properties of two-dimensional electron gases （2DEG） in AlxGa1-x N/GaN heterostructures with different Al compositions are investigated by magnetotransport measurements at low temperatures and in high magnetic fields. It is found that heterostructures with a lower Al composition in the barrier have lower 2DEG concentration and higher 2DEG mobility.展开更多
The influence of polarization-induced electric fields on the electron distribution and the optical properties of intersubband transitions （ISBT） in AlxGa（1-x）N/GaN coupled double quantum wells （DQWs） is investig...The influence of polarization-induced electric fields on the electron distribution and the optical properties of intersubband transitions （ISBT） in AlxGa（1-x）N/GaN coupled double quantum wells （DQWs） is investigated by self-consistent calculation. It is found that the polarization-induced potential drop leads to an asymmetric potential profile of AlxGa（1-x）N/GaN DQWs even though the two wells have the same width and depth. The polarization effects result in a very large Stark shift between the odd and even order subbands,thus shortening the wavelength of the ISBT between the first odd order and the second even order （1odd-2 ） subbands. Meanwhile, the electron distribution becomes asymmetric due to the polarization effects, and the absorption coefficient of the 1odd-2 ISBT decreases with increasing polarization field discontinuity.展开更多
Magnetotransport measurements are carried out on the A1GaN/A1N/GaN in an SiC heterostructure, which demon- strates the existence of the high-quality two-dimensional electron gas （2DGE） at the A1N/GaN interface. Whil...Magnetotransport measurements are carried out on the A1GaN/A1N/GaN in an SiC heterostructure, which demon- strates the existence of the high-quality two-dimensional electron gas （2DGE） at the A1N/GaN interface. While the carrier concentration reaches 1.32×10^13 cm^-2 and stays relatively unchanged with the decreasing temperature, the mobility of the 2DEG increases to 1.21 × 10^4 cm2/（V.s） at 2 K. The Shubnikov-de Haas （SdH） oscillations are observed in a magnetic field as low as 2.5 T at 2 K. By the measurements and the analyses of the temperature-dependent SdH oscillations, the effective mass of the 2DEC is determined. The ratio of the transport lifetime to the quantum scattering time is 9 in our sample, indicating that small-angle scattering is predominant.展开更多
文摘Magnetotransport properties of two-dimensional electron gases （2DEG） in AlxGa1-x N/GaN heterostructures with different Al compositions are investigated by magnetotransport measurements at low temperatures and in high magnetic fields. It is found that heterostructures with a lower Al composition in the barrier have lower 2DEG concentration and higher 2DEG mobility.
文摘The influence of polarization-induced electric fields on the electron distribution and the optical properties of intersubband transitions （ISBT） in AlxGa（1-x）N/GaN coupled double quantum wells （DQWs） is investigated by self-consistent calculation. It is found that the polarization-induced potential drop leads to an asymmetric potential profile of AlxGa（1-x）N/GaN DQWs even though the two wells have the same width and depth. The polarization effects result in a very large Stark shift between the odd and even order subbands,thus shortening the wavelength of the ISBT between the first odd order and the second even order （1odd-2 ） subbands. Meanwhile, the electron distribution becomes asymmetric due to the polarization effects, and the absorption coefficient of the 1odd-2 ISBT decreases with increasing polarization field discontinuity.
基金Project supported by the National Basic Research Program of China (Grant No.2011CB309606)
文摘Magnetotransport measurements are carried out on the A1GaN/A1N/GaN in an SiC heterostructure, which demon- strates the existence of the high-quality two-dimensional electron gas （2DGE） at the A1N/GaN interface. While the carrier concentration reaches 1.32×10^13 cm^-2 and stays relatively unchanged with the decreasing temperature, the mobility of the 2DEG increases to 1.21 × 10^4 cm2/（V.s） at 2 K. The Shubnikov-de Haas （SdH） oscillations are observed in a magnetic field as low as 2.5 T at 2 K. By the measurements and the analyses of the temperature-dependent SdH oscillations, the effective mass of the 2DEC is determined. The ratio of the transport lifetime to the quantum scattering time is 9 in our sample, indicating that small-angle scattering is predominant.
