Effect of polarization field on intersubband transition in AlGaN/GaN quantum wells

The effect of the built-in field caused by the piezoelectric effect and the spontaneous polarization inherent in nitride quantum wells on the intersub band transition (ISBT) is studied. Measured intersubband absorption wavelen gths of Al0.65Ga0.35N/GaN multiquantum wells suggest the existence of a str ong field of about 2 MV/cm. For thick wells, the built-in field in the well reduces the effective well width, which drastically shortens the ISBT wave length and increases the intersubband relaxation time. For thin wells, the strong field in barriers reduces the effective barrier height, which affect s the formation of the second subband. Reduction in the field strength in t he barriers is important in achieving a short wavelength ISBT.