Hg sub (1-x) Cd sub x Te-Based Multiple Quantum Wells for the 2.5 - 3micron Wavelength Range
10 October 1988
The wavelength regime of 2.5 - 3micron is of interest because it coincides with the anticipated minimum loss for fluoride fibers that are being developed. We have grown Hg sub (1-x) Cd sub x Te/CdTe multiple quantum well structures in this wavelength range by molecular beam epitaxy, and have measured their properties by photoluminescence and absorption. Sharp excitonic features, consistent with well width fluctuations on the order of one monolayer, are observed at low temperatures. These features broaden by 40 meV as the temperature is raised from 2 K to room temperature. The temperature dependence of the exciton energy is in excellent agreement with the variation reported for the alloy composition that is in the quantum well. We have found that, with careful design of the multiple quantum well structure, we can minimize interdiffusion during growth. Films have been grown at a substrate temperature of 185C which show x-ray satellite peaks out to fourteenth order. Post-growth annealing experiments show that these structures are far less subject to interdiffusion than are HgTe/CdTe superlattices.