Spatial localization and diffusion of atomic silicon in delta-doped GaAs

Abstract

Spatial localization and diffusion of atomic Si is studied inσ-doped GaAs by employing capacitance-voltage (CV) measurements and rapid thermal annealing. It is found that diffusion and segregation are irrelevant inσ-doped GaAs grown at temperatures below 550° C. Combination of rapid thermal annealing and capacitance-voltage profiling is a novel method which is most sensitive to diffusion and it is shown that this method is able to detect diffusion on a length scale of 10A. CV-profile widths broaden from⪯40A to 137A upon rapid thermal annealing at 1000° C for 5 sec. The diffusion coefficient and the activation energy of atomic Si-diffusion in GaAs are determined to beDo = 4 × 10−4 cm2/s andEa = 2.45 eV, respectively. The basic theory of CV-measurements on a quantum-mechanical electron system is developed.