PLASMA MOVPE OF TERNARY AND QUATERNARY LAYERS

The present paper reports results on the growth of GaAsP, GaInP, GaInAs and GaInAsP in plasma MOVPE (metalorganic vapor phase epitaxy). The basic aim of this study was to investigate the effects of plasma precracking of the group V hydrides (AsH3 or PH3) on the composition of the deposited material. For GaInAs a significant effect of the presence of AsH3 cracking products on the incorporation of the different group III elements is observed. No such dependence is found for precracking of PH-3 during growth of GaInP. For the epitaxy of GaAsP or GaInAsP the competitive incorporation of the two different group V elements is a matter of interest. When plasma precracking of the P precursor PH3 is applied, the PH3 to AsH3 ratio can be reduced compared to conventional MOVPE. A high P content in the deposit is obtained, but the composition of the material is less sensitive to temperature variations. Consequently, the use of the plasma approach towards growings GaInAsP yields an improved homogeneity of the solid composition in the case of the quaternary material. For all semiconductors under study, the plasma approach yields layers of a quality comparable to the best reported in the literature.