Anomalous temperature distribution created in a semiconductor by strongly absorbed light

Abstract

The distribution of the lattice temperature in a semiconductor plate is described for the case when one of the plate surfaces is illuminated by strongly absorbed light. It is shown that the temperature of the illuminated surface and the average temperature of the sample became lower than the temperature of the surrounding medium when the diffusion flux of carriers drags phonons and certain boundary conditions are used.

The influence of phonon drag by diffusion carrier flux on the photoacoustic effect in semiconductors

“…The surface x a = is in ideal thermal contact with a thermostat, whose temperature is 0 T and the SRR at the shadow surface is extremely high. The gradient of the EHP concentration and the DC of phonon heat flux have maximum values in this case [20]. It is shown in [21] that maximum temperature variation on the illuminated surface takes place at high light absorption coefficient.…”

“…is the phonon drag coefficient by EHP diffusion flux [19,20], s is the sound velocity in the semiconductor, and d v is the frequency of phonon scattering by defects. Note that the expressions for p j and W are obtained using the assumption…”

“…The inequality 1 β can be strongly fulfilled, because the characteristic value of r β is about 10 9 . The condition 1 β means the presence of both phonon drag by EHP diffusion flux [19,20] and "thermo-drag" of carriers by phonon heat flux [23,24].…”

“…However, it is shown in [19] that under certain conditions non-equilibrium carriers also pass the directed part of momentum to the phonons. The diffusion component (DC) of the phonon heat flux occurs when the thermal drag of phonons takes place [20]. A new channel of heat removal (DC of phonon heat flux) essentially changes the distribution of the semiconductor lattice temperature [20,21].…”

“…The diffusion component (DC) of the phonon heat flux occurs when the thermal drag of phonons takes place [20]. A new channel of heat removal (DC of phonon heat flux) essentially changes the distribution of the semiconductor lattice temperature [20,21]. In particular, semiconductor cooling is possible when one sample surfaces is illuminated by strongly absorbed light and phonon diffusion drag by electron-hole pair (EHP) flux is large.…”