Study of the Irradiance- and Temperature-Dependence of Mid-Wave- Infrared (MWIR) Absorption in Indium Antimonide (InSb); Master's thesis

摘要

This work entails further investigation of the absorption of photons in indium antimonide (InSb). Previously work at the Air Force Institute of Technology (AFIT) attributed laser blooming effects in InSb focal plane arrays (FPA's) to the Burstein-Moss effect. The contributing effect is from a decrease in the absorption of the InSb material, such that the transmitted optical energy scatters off the integrated circuitry beneath the InSb thin film back into the optical system. To evaluate this, irradiance-dependent laser- absorption experiments were performed on thinned, InSb wafers prior to their FPA fabrication. The samples were illuminated with a focused CO2 laser at 4.6 micrometers, and translated along the optical axis to vary the irradiance. A control process to remotely manage the experiment's apparatuses during data collection has been developed utilizing LabView 8.5. The transmission of the InSb sample was measured at different laser powers and temperatures. As the temperature decreases for a determined laser irradiance, it has been observed that the absorption decreases nonlinearly. A model of the absorption-saturation phenomena is also developed so that agreement between the measured and modeled results can be studied for the carrier lifetime and density of carriers.