EFFECT OF WAFER CLEAVAGE ON COMPOSITION OF INGAASP GROWN ON INP BY LOW-PRESSURE MOCVD

The compositional uniformity of lambda = 1.3-mu-m InGaAsP grown over 50 mm diameter substrates is severly degraded if the substrate is cleaved. The effect of cleaves either parallel or perpendicular to the direction of gas flow in the reactor has been observed. An increase in the phosphorus mole fraction of the quaternary alloy is noted near the cleave, and is attributed to an increase in the decomposition of the PH3 precursor gas at the cleavage site. The decomposition products of PH3 pyrolysis then re-enter the gas stream, making the cleave a PH3 cracker during low pressure MOCVD crystal growth.