Hot‐electron second‐harmonic generation in non‐degenerate CdS at low temperatures

Abstract

AbstractIn order to study analytically hot‐electron second‐harmonic generation due to high‐frequency electromagnetic waves in non‐degenerate CdS the Boltzmann transfer equation has been solved in the relaxation time approximation. Scattering of electrons by acoustic phonons (both isotropic deformation and anisotropic piezoelectric interactions) has been taken into account. To get an idea of the order of magnitude of the second‐harmonic generated, some calculations have been performed and the results are presented in form of graphs. The plot of the second‐harmonic intensity versus applied dc electric field shows a maximum. This means that there is an optimum value of the dc field for which the second‐harmonic yield is maximum. At very low temperatures and for weak dc fields, the second‐harmonic component exhibits anisotropy with respect to the direction of the applied dc electric field. Anisotropy of 0.80% can be observed for the optimum value of the dc field (Ed = 0.6 V/cm) at liquid helium temperature. The anisotropy effect vanishes as the lattice temperature (or the dc field) increases. For the optimum value of the dc electric field it has been found that the percentage of harmonic generation is ≈ 30%, for incident wave fields of 0.06, 0.57, and 1.62 V/cm at 4.2, 20, and 40 °K, respectively.