Characterization of conducting GaAs multilayers by infrared spectroscopy at oblique incidence

The electrical and geometric properties of GaAs multilayer structures are measured nondestructively by infrared reflectance spectroscopy (50-5000 cm sub -1). Using oblique incidence and both s- and p-polarizations of the probing beam, carrier concentration of the GaAs substrate are determined. The main structures in the spectra are due to phonon restrahlen bands, Fabry-Perot interferences and the zeros of the dielectric function leading to dips in the reflectance (Berreman Mode). The results compare favorably with a depth-resolved secondary ion mass spectrometric (SIMS) sample analysis. The range of applicability of the method is discussed.