Calculations of Two-Photon Conductivity in Semiconductors

Abstract

The photoconductivity produced in some direct-band-gap semiconductors by the two-photon absorption process is investigated theoretically and found to be a very complicated function of the crystal parameters, the excitation photon energy, and the light excitation intensity. An application of the theory to a GaAs crystal is carried out.

Transient photocurrent induced in gallium nitride by two-photon absorption

“…In the case of high-power laser applications, calculations show that two-photon absorption in pristine semiconductors is a fundamental limitation regarding third-order nonlinear processes such as all-optical switching phenomena in the photon energy range between E gap/2 -E gap . 9,10 In our study, the magnitude of ␤() was observed to be negligible for photon energies below E gap/2 ; above this energy, the dispersion displayed a functional dependence on photon energy that has been observed in both zinc blende and wurtzite semiconductor crystals. In addition to the technological implications, a number of recent nonlinear absorption studies of semiconducting structures has also shown that ␤() can be used as a complementary spectroscopic probe to the more common linear absorption measurements since the selection rules for the two processes are different.…”