HIGH-QUALITY ALXGA1-XAS GROWN BY ORGANOMETALLIC VAPOR-PHASE EPITAXY USING TRIMETHYLAMINE ALANE AS THE ALUMINUM PRECURSOR

High quality Al(x)Ga1-x(As) has been grown by low-pressure (30 Torr) organometallic vapor phase epitaxy (OMVPE) using a novel precursor, trimethylamine alane (TMAA1), as the aluminum source. The epilayers exhibited featureless surface morphology, very strong room-temperature photoluminescence (PL), and excellent compositional uniformity (x = 0.235 +/- 0.002 over a 40 mm diameter). The residual carbon incorporation, which determined the background doping, depended largely upon the choice of gallium precursor. Using triethylgallium, carbon incorporation could be largely suppressed (]C[)<< 10(16) cm-3). The carbon-related emission intensity was less than the bound exciton emission in low-temperature (1.6 K) PL even at excitation powers as low as 50 mu-W cm-2. By sharp contrast, the use of trimethylgallium led to much higher C concentration (2-5 X 10(17) cm-3). Under appropriate conditions, therefore, the use of TMAA1 produces extremely high purity AlGaAs of superior quality to A1GaAs grown using conventional precursors.