Electric field dependence of intersubband transitions in GaAsAlGaAs single quantum wells

The effects of applied electric fields on intersubband (ISB) transitions in modulation-doped n-i-n and p-i-n type GaAsAlGaAs single quantum well (SQW) structures are studied experimentally using Fourier Transform InfraRed (FTIR) spectroscopy. The n-i-n SQW devices exhibit a red shift of 0.7 meV in the ISB transition energy and a 12% decrease in the integrated absorbance at the maximum applied bias of 3.2 V with reference to their zero bias values, most of which is attributed to a rise in the device temperature due to Joule heating owing to the current flowing through the device. The p-i-n SQW devices exhibit strong quenching of the absorption when a negative bias is applied, while there was no observable shift in the ISB transition energy.