Characterization and modeling of the infrared properties of GaP and GaAs

摘要

The experimental characterization of multiphonon absorption in polycrystalline GaP and GaAs as a function of temperature and frequency is presented. Because GaP and GaAs have moderate bandgaps, free carrier absorption is examined at high temperature as well. The longwave transparency and excellent thermal and mechanical properties of GaP make it a candidate for future high-stress environment applications. In this paper, a broadband FTIR transmissometer is used with a frequency range from 500 to 5000 cm~(-1) for GaP and 400 to 5000 cm~(-1) for GaAs. Spectral measurements were performed from 10 to 800 K for GaP and 10 to 295 K for GaAs. In addition, high temperature laser transmittance measurements using HeNe lasers (632.8 nm and 3.39 μm) and a CO_2 (10.6 μm) laser were conducted up to 1100 K. Using this experimental data set, an updated multiphonon and free carrier absorption model is developed that represents the experimental data over all temperatures and frequencies.