Epitaxial growth of gallium arsenide prepared by low-pressure metal-organic chemical vapour deposition at low temperatures

Abstract

The low-pressure metal-organic chemical vapour deposition (LPMOCVD) technique has been investigated previously as a growth method for compound semiconductors, offering the possibility of selective epitaxy and the potential advantage of better controllability for changing the doping level and the alloy composition. Low-temperature growth is also desirable to reduce the carbon incorporation generated by the decomposition of the organic radicals. In this article we report for the first time the epitaxial growth of gallium arsenide (GaAs) by LPMOCVD at temperatures as low as 510 °C. The vertical reactor that was developed by the authors employs conventional precursors such as trimethylgallium and arsine. By carefully choosing the growth parameters, we were able to grow high-quality GaAs epilayers with good surface morphology at temperatures as low as 510 °C. The carbon incorporation is shown to decrease with decreasing growth temperature without deterioration of the film quality. By carefully controlling the purity of the sources and the gas flow dynamics, we reduced the deep level impurity concentration and obtained reproducible n-type material with residual net donor concentration of 4.4 × 1014 cm−3 and mobility of 92 000 cm2 V−1 s−1 at 77 K.