Diffusion, solubility, and electrical activity of Co and Fe in InP

Abstract

The results of diffusion, solubility, and electrical activity of Fe and Co in InP by radioactive and voltage-capacitance measurement methods are given. The profiles of Co and Fe in InP cannot be described by the standard error function and consist of two regions between which the minimum of doping concentration is identified at high temperatures. The efficient diffusion coefficients in the range of temperatures 600 to 950 °C are approximated by the expressions: D = D0 exp ( ΔE/kT) with parameters D0 = 0·9 cm2/s and ΔE = (1.8 ± ± 0·2) eV for Co, and D0 = 3.0 cm2/s and ΔE = (2 ± 0·3) eV for Fe in InP. The solubility of Co and Fe in the same range of temperatures is approximated by the equation N = = N0 exp (- ΔH/kT) with parameters N0 = 1·3 × 1021 cm−3 and ΔH = (1.0 ± 0·2) eV for Co, and N0 = 3 × 1021 cm−3 and ΔH = (0.8 ± 0·2) eV for Fe in InP. The experimental results can be interpreted by means of a model of dissociative diffusion taking into account the variations of stoichiometric composition of the semiconductor as a result of the volatile component evaporation at high temperature annealing. The problem of the charged state of vacancies in InP and their interaction with diffusing doping atoms is discussed.