THE EFFECTS OF OXYGEN IMPURITY IN TMA ON ALGAAS LAYERS GROWN BY MOVPE

We have investigated the effects of methoxide (-OMe), one of the main oxygen impurities in trimethylaluminum (TMA), on AlGaAs layers grown by metalorganic vapor phase epitaxy (MOVPE). -OMe enriched TMA was prepared by partial oxidation to yield 5300 wt.ppm of -OMe in the liquid phase TMA. The vaporization behavior of -OMe in TMA was studied. There was a strong correlation found between the concentration of -OMe in the TMA and that of oxygen atoms in the AlGaAs layers. The electrical characteristics of the layers co-doped with disilane and -OMe showed that oxygen-related centers compensated the Si donor. The effects of Al composition, growth temperature and As/(Al + Ga) ratio on the behavior of oxygen incorporation were also investigated. It was found that the incorporation behavior of the oxygen was similar to that of other group VI (S, Se, Te) impurities.