ABCS Quantum Wells for Coherent THz Wave Generation

摘要

The goal of this project was to construct a compact terahertz (THz) source based on antimonide-based compound semiconductor (ABCS) quantum wells. The large conduction band offsets achievable with these materials make it possible to design and fabricate unique structures in which both near-infrared pumping and THz emission energies resonate with intersubband transitions. This all-intraband-transition scheme provides the ability to tune the THz emission wavelength entirely independently of the band gaps. Single and double quantum well structures were grown by molecular beam epitaxy and characterized spectroscopically to determine their absorption and gain spectra. The results were compared with detailed theoretical modeling and simulations. THz generation was attempted by difference frequency mixing in resonant double quantum wells. No THz emission was detected. However, this project has made unique contributions to the experimental and theoretical understanding of intersubband resonances over a wide range of temperatures, carrier densities, and well widths. This new understanding will have a significant impact on the many intersubband-based mid- and far-infrared emitters and detectors, and in particular on short-wavelength ABCS quantum cascade lasers.