Mid-Infrared Intersubband Absorption from p-Ge Quantum Wells Grown on Si Substrates

摘要

Mid-infrared intersubband absorption from p-Ge quantum wells with Si_(0.5)Ge_(0.5) barriers grown on a relaxed Si_(0.2)Ge_(0.8) buffer on a Si substrate is demonstrated from 6 to 9 μm wavelength at room temperature and can be tuned by adjusting the quantum well thickness. Fourier transform infra-red transmission demonstrate clear absorption peaks corresponding to intersubband transitions among confined hole states. The work indicates an approach that will allow quantum well intersubband photodetectors to be realized on Si substrates in the important atmospheric transmission window of 8-13 μm where many chemical and biological molecules have unique molecular absorption lines for spectroscopic identification.