The effect of compensation on the pair spectra from Gehyphen;dopedphyphen;type Ga0.60Al0.40As grown by liquidhyphen;phase epitaxy under highhyphen;purity He ambient is investigated. It is found that when the amount of compensation is high, pair transitions occur mainly via the deep GeAsacceptors at low excitation levels. The addition of oxygen (0.3ndash;0.9 ppm) or H2(11percnt;) to the He ambient during growth reduces the compensation, with hydrogen found to be more effective than O2. For reduced compensation, pair transitions via the shallow acceptors due to residual C and Si are favored. The compensation is due to the presence of residual donors such as S whose concentration varies from wafer to wafer causing fluctuations in the relative intensities of pair transitions. Since strong pair transitions involving shallow acceptors reflect low concentration of compensating donors and thus improved conductivity in theplayers, the use of H2in the He ambient gas during the growth of (GaAl)As doublehyphen;heterolaser structures should be advantageous.
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