Optical and Transport Properties of InAs/AlxGa1-xSb Quantum Well System

In this thesis, we report the studies on optical and electrical properties of type-II InAs/AlxGa1-xSb multiple quantum wells. The electron concentration and resistivity were studied by van der Pauw/Hall measurement. The optical transitions were investigated by photoluminescence (PL) measurement. Transmission spectra studied by Fourier transform infrared measurement (FTIR) were also reported.
The band structure of samples changed substantially after removing the cap layer, and the properties of the as-grown sample with that of the etched sample was compared.
Base on the temperature dependence of the electron concentration in InAs quantum well, we find the activation energy for electron ionization. The main peak of PL spectrum in the infrared range is due to the subband transition between the InAs well and AlxGa1-xSb barrier in the cap layers. The two small absorption peaks in transmission spectra can be attributed to GaSb and InAs TO phonons. The infrared absorption by InAs TO phonon provides a nondestructive way to determine the layer thickness of the InAs quantum well.