Preparation of InAs by annealing of two-layer In-As electrodeposits

In this work, we investigate the galvanostatic electrodeposition of In from aqueous solutions on electrodeposited amorphous arsenic substrates and the temporal variation of the composition of the In-As two-layer subjected to annealing. Surface morphology, composition and crystallographic structure of the deposits before and after annealing were analysed by scanning electron microscopy (SEM), laser profilometry, X-ray energy dispersive spectroscopy (EDX) and X-ray diffraction (XRD). The amorphous arsenic film was structurally characterised, determining the radial distribution function (RDF) and the main interatomic distances. The annealing procedure consisted in holding the samples in vacuo at 60, 100 and 140 degreesC for increasing times. The results showed the formation of InAs, owing to reaction-diffusion going on at the In-As interface. The values of the In diffusion coefficient in the range 60-140degreesC (from 4 x 10(-21) to 2.2 x 10(-18) m(2) s(-1)) were evaluated from XRD data with a simple reaction-diffusion model. The activation energy (90 kJ mol(-1)) and the pre-exponential factor (4.5 x 10(-7) m(2) s(-1)) were also estimated. The results were discussed in connection with those previously obtained regarding the indium diffusion process into amorphous antimony with formation of InSb. (C) 2003 Elsevier B.V. All rights reserved.