In situ measurements of GaN photoluminescence at metal and electrolyte contacts

The characteristics of GaN photoluminescence have been measured in situ as a function of potential at gold and electrolyte contacts. In the case of the GaN/electrolyte contact, it was found that for aqueous KOH and sulfate-based electrolytes over a pH range of 0-14, the photoluminescence intensity increased sharply at applied potentials close to the flatband value. In contrast, no significant increase in photoluminescence intensity above the open-circuit value was measured for the GaN/Au contact. In this case, the photoluminescence intensity was reduced under reverse biased conditions and the photoluminescence was effectively quenched at reverse potentials above 7.5 V.