Electrical properties and thermal stability of semi-insulating InP crystals with different iron content

Results of electrical measurements carried out on different InP:Fe crystals are discussed. The Hall mobility of high-resistivity Fe-doped InP wafers is shown to vary over a wide range. On the basis of their mobility, the high-resistivity samples are classified into three groups. The results of electrical measurements on annealed InP and the correlation between the electrical characteristics of as-grown and annealed InP are also discussed. Semi-insulating InP is shown to exhibit different compensation regimes and electrical characteristics, according to the concentration of Fe incorporated and residual shallow levels. It is also shown that as-grown InP, with a compensation ratio NFe/ (Nd-Na) in the 1.2 to 2.5 range, has the highest mobility and resistivity. Other high-resistivity materials, with higher compensation ratios, show reduced Hall mobilities. The thermal annealing produces considerable iron diffusion. An acceptable thermal stability is found in samples where NFe > Nd > Na. Heavily Fe-doped InP can be positively influenced by thermal treatments and exhibit improved electrical characteristics.