Effects of residual impurities on Zn electrical activity in Zn-doped InGaAlP grown by metalorganic chemical vapor deposition

The effects of residual impurities, such as hydrogen and oxygen, on Zn electrical activity have been studied for Zn-doped In 0.5(Ga 1− x Al x ) 0.5P grown by low-pressure metalorganic chemical vapor deposition. Zn electrical activity with a p-type cap l ayer grown on Zn-doped InGaAlP was found to be quite low and a high concentration of hydrogen was detected in Zn-doped InGaAlP. Zn electrical activity with an n-type cap layer was relatively high and no hydrogen was detected. The difference in Zn electrical activity with the conduction type of the cap layer may be a result of hydrogen passivation of Zn acceptors. The oxygen concentration in the InGaAlP increased abruptly for x > 0.4. The decrease in Zn electrical activity with increasing x correlated strongly with the increase in oxygen concentration with x, while Si electrical activity was unchanged with varying x. Oxygen might act as a deep donor in InGaAlP, compensating for Zn acceptors. It was thus demonstrated that Zn electrical activity in InGaAlP was significantly affected by the presence of hydrogen and oxygen.