Abstract The influence of applied electric fields on the absorption coefficient and subband distances in asymmetrical AlN/GaN coupled double quantum wells (CDQWs) has been investigated by solving Schr?dinger and Poisson equations self-consistently. It is found that the absorption coefficient of the intersubband transition (ISBT) between the ground state and the third excited state (1odd-2even) can be equal to zero when the electric fields are applied in asymmetrical AlN/GaN CDQWs, which is related to applied electric fields induced symmetry recovery of these states. Meanwhile, the energy distances between 1odd-2even and 1even-2even subbands have different relationships from each other with the increase of applied electric fields due to the different polarization-induced potential drops between the left and the right wells. The results indicate that an electrical-optical modulator operated within the opto-communication wavelength range can be realized in spite of the strong polarization-induced electric fields in asymmetrical AlN/GaN CDQWs.
Received: 29 December 2008
Revised: 07 April 2009
Accepted manuscript online:
Fund: Project supported by the National
Natural Science Foundation of China (Grant Nos 60806042, 10774001,
60736033, 60890193 and 60628402), National Basic Research Program of
China (Grant Nos 2006CB604908 and 2006CB921607), the Research Fund
for the Doctoral Program of Higher Education in China (Grant Nos
200800011021 and 20060001018), and Beijing Natural Science
Foundation (Grant
No 4062017).
Cite this article:
Cen Long-Bin(岑龙斌), Shen Bo(沈波), Qin Zhi-Xin(秦志新), and Zhang Guo-Yi(张国义) Influence of applied electric field on the absorption coefficient and subband distances in asymmetrical AlN/GaN coupled double quantum wells 2009 Chin. Phys. B 18 3905
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