Deep levels in unintentionally doped Al0.48In0.52As layers epitaxially grown on InP substrates by low-pressure MOCVD have been investigated as a function of growth temperature (Tg ranging from 570 to 690 °C). Two different origins for the residual carrier concentration are deduced depending on Tg: i) low growth temperatures favor the creation of a deep donor located at Ec-(0.13±0.04) eV; ii) At higher Tg, a preferential incorporation of a shallow donor occurs, which can be attributed to silicon by SIMS measurements. The oxygen contamination deduced by SIMS and the electrical characteristics of the AlInAs layers do not appear to be correlated.
