Structural evaluation of low-temperature-grown InGaAs crystals on (0 0 1) InP substrates

Abstract

Through transmission electron microscopy and related techniques, we performed structural evaluation of low-temperature grown (LTG) InGaAs crystals on (001) InP substrates. These crystals were grown at a substrate temperature of 200–250 °C. The results revealed that As precipitates (diameter: 7–15 nm) are generated in undoped InGaAs crystals (mainly near the interface between the epi-layer and the substrate) after annealing at 550 °C for 1 h. However, no precipitates were observed in Be-doped LTG InGaAs crystals before and after annealing. Moreover, in the case of Be-doped LTG-InGaAs crystals highly mismatched with the InP substrate, we observed no preferential generation of precipitates at the core of the misfit dislocations. Based on these findings, the generation mechanism of the precipitates in undoped LTG-InGaAs crystals during the annealing process and physical origin for the absence of precipitates in Be-doped LTG-InGaAs crystals after the annealing are discussed. Apart from the precipitates, we have also found that surface defects elongated in the [110] direction are formed in the InGaAs crystal, which are presumably generated by the evaporation of As-atoms from the surface during annealing.