Incorporation of aluminum and oxygen in dimethylaluminum methoxide doped GaAs during organometallic vapor phase epitaxy

Abstract

Dimethylaluminum methoxide (DMA1MO) was used as a deep level dopant source in GaAs epilayers grown by organometallic vapor phase epitaxy (OMVPE). The compound is stable, does not exhibit gas phase reactions in all investigated deposition conditions, and does not degrade surface morphology even at doping levels in excess of 10 19 cm -3. Incorporation of aluminum and oxygen into the epilayer was studied by secondary ion mass spectroscopy (SIMS) on multi-layered samples as a function of growth conditions: growth temperature, reactor pressure, dopant mole fraction in the gas phase, and growth rate. Both oxygen and aluminum are incorporated during deposition with oxygen concentration always lower but approaching that of aluminum at temperatures below 500°C. At higher growth temperatures, [O]/[Al] ratio decreases exponentially with activation energy of 2.0 eV. Incorporation of oxygen exhibits superlinear behavior at higher DMA1MO mole fractions.