Epitaxial Growth of High-Purity GaAs by Low-Pressure MOCVD

High-purity GaAs epitaxial layers were reproducibly obtained at operating pressures lower than conventional low-pressure MOCVD. The epitaxial layer grown at 17 Torr exhibited a high mobility of 105,000 cm2/V·sec at 77 K and a fine exciton structure in the low-temperature PL spectrum. The conductivity of epitaxial layers grown at 8 Torr changed from p-type to n-type as the [AsH3]/[TMG] ratio increased. PL spectra indicated that carbon is the dominant acceptor and that carbon concentration and fine exciton structure depend strongly upon the [AsH3]/[TMG] ratio.