Noncontact laser control of electric-physical parameters of semiconductor layers
- 1 — Ph.D., Dr.Sci. professor Saint-Petersburg Mining University
- 2 — Ph.D. associate professor Saint-Petersburg Mining University
Abstract
Non-contact non-destructive laser-interferometric methods for measuring several electrophysical parameters of semiconductor and dielectric layers are proposed. They are the lifetime of charge carriers for electrons and holes separately; parameters of recombination centers, namely their concentration and capture cross-sections; bulk volume lifetime and rate of surface recombination, as well as the diffusion length of charge carriers. The methods are based on the interference-absorption interaction in a semiconductor of two laser radiations with different wavelengths. Short-wave injection radiation generates additional charge carriers in the material, which leads to a change in its optical constants at the wavelength of the other – long-wavelength probing laser radiation – and to modulation of this radiation as it passes through the sample of the studied material. The means for implementing the proposed methods and methods for processing the modulation signal for determining the parameters of the investigated samples are developed. The methods have been successfully tested on samples of such materials as germanium, silicon, indium antimonide and cadmium-mercury-tellurium alloy. It is shown that the methods can be used both in scientific research and electronic industry.