Distribution of the excitation density in electron-beam-pumped semiconductor lasers

The Monte Carlo method is used to calculate the spatial distribution of the density of the absorbed energy and the dimensions of the excited region in GaAs and CdS semiconductor lasers excited by beams of electrons of energies from 10 keV to 20 MeV. The results of the calculations are used to derive an approximate analytic expression convenient for the determination of the distribution of the density of the absorbed energy with depth in the material in a wide range of electron energies. A considerable reduction in the maximum value of the density of the absorbed energy of the pump electrons occurs when the electron beam diameter is small. This is one of the reasons for the increase in the lasing threshold (expressed in terms of the pump current density) on reduction in the size of the electron beam used to excite a laser.