Laser beam heating and high temperature band-to-band luminescence of GaAs and InP

Abstract

High temperature band-to-band luminescence of GaAs and InP excited by an argon ion laser beam was used as a probe to measure the temperature inside of the laser spot. First, the high temperature luminescence with external heating by an oven was studied, and the resulting dependence of luminescence and band gap on the temperature was used to investigate the case of laser heating. It was found that lattice heating is the most important influence on the luminescence spectra for strong cw laser excitation, and that the temperature of the lattice can be determined with high precision due to the high sensitivity of the luminescence band energy to the lattice temperature. The temperature inside of the laser spot as a function of laser power was measured. The temperature is lower than anticipated from the current theories for cw laser heating. This disagreement can be explained by the contribution of photoexcited carriers to the thermal conductivity, which was not considered by theories.