Nanosecond-Pulse Annealing of Heavily Doped Ge:Sb Layers on Ge Substrates

Abstract

To produce heavily doped epitaxial layers, amorphous Ge:Sb films with a thickness of 150 and 300 nm are vacuum-deposited on Ge substrates and are exposed to pulsed nanosecond irradiation of high-power laser (λ = 0.69 μm) or ion (C⁺ or H⁺) beams. In the course of laser processing, the irradiated region is optically probed with the registration of the reflection of the probe beam R(t) to control the aggregate state of the film. As a result of rapid crystallization, polycrystalline or epitaxial Ge:Sb layers of different thicknesses are formed from the melt. Computer simulation of the heating and phase transitions of an amorphous Ge film on a crystalline Ge substrate is carried out, as well as the diffusive redistribution of the impurity (Sb) under pulsed treatments. We showed that, due to the volumetric release of the energy of ion beams, it is possible to control the distribution of the Sb impurity up to a depth of 1.5 μm. The simulation results are in good agreement with the experiment.