EPITAXIAL-GROWTH OF GALLIUM-ARSENIDE PREPARED BY LOW-PRESSURE METAL-ORGANIC CHEMICAL-VAPOR DEPOSITION AT LOW-TEMPERATURES

The low-pressure metal-organic chemical vapour deposition (LPMOCVD) te chnique has been investigated previously as a growth method for compou nd semiconductors, offering the possibility of selective epitaxy and t he potential advantage of better controllability for changing the dopi ng level and the alloy composition. Low-temperature growth is also des irable to reduce the carbon incorporation generated by the decompositi on of the organic radicals. In this article we report for the first ti me the epitaxial growth of gallium arsenide (GaAs) by LPMOCVD at tempe ratures as low as 510-degrees-C. The vertical reactor that was develop ed by the authors employs conventional precursors such as trimethylgal lium 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-degrees-C. The carbon incorporation is s hown to decrease with decreasing growth temperature without deteriorat ion of the film quality. By carefully controlling the purity of the so urces and the gas flow dynamics, we reduced the deep level impurity co ncentration and obtained reproducible n-type material with residual ne t donor concentration of 4.4 X 10(14) cm-3 and mobility of 92 000 CM2 V-1 s-1 at 77 K.