Effect of Polarization Field on Intersubband Transition in AlGaN/GaN Quantum Wells

Abstract

The effect of the built-in field caused by the piezoelectric effect and the spontaneous polarization inherent in nitride quantum wells on the intersubband transition (ISBT) is studied. Measured intersubband absorption wavelengths of Al 0.65 Ga 0.35 N/GaN multiquantum wells suggest the existence of a strong 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 wavelength and increases the intersubband relaxation time. For thin wells, the strong field in barriers reduces the effective barrier height, which affects the formation of the second subband. Reduction in the field strength in the barriers is important in achieving a short wavelength ISBT.