Thermodiffusion in Si-X-Ge33As12Se55 (X:Sb,Bi) interface

Abstract

Thin films of 1,000-nm thickness were deposited from Ge33As12Se55 glass by flash evaporation onto n-Si substances coated with thermally evaporated antimony or bismuth layer of 10-nm thickness. Thermal annealing of the structure has been conducted at a temperature of 450 K during 90 minutes. The main parameters of the thermodiffusion processes have been determined by the capacitor-voltage characteristics. Energy bands discontinuity on the n-Si-X-Ge33As12Se55 interface after thermodiffusion of antimony and bismuth atoms have been found to be for the conduction band 0.61 and 0.86 eV, and for the valence band 0.08 and 0.17 eV, respectively. The diffusion in Ge33As12Se55 film for antimony atom differs from that for the bismuth ones. It has been found that the diffusion processes were more intensive for antimony atoms and both types of the impurity atom exhibited nonuniform profiles. The diffusion coefficients for antimony and bismuth atoms in the near- surface layer of Ge33As12Se55 film have been found to be respectively, 2.1 X 10-14 and 2.3 X 10-15 cm2/s. Inside the film the coefficients are 3.0 X 10-14 and 1.2 X 10-13 cm2/s. The higher intensity of the diffusion for antimony atoms has been related to the lower values for their atomic radii.