LIGHT-INDUCED DEFECTS IN PLASMA-HYDROGENATED INP-ZN

PhotoLuminescence (PL) measurements are used to investigate the effect s of a H-2 plasma treatment in heavily doped p-type InP: Zn. Beside th e large decrease in free hole concentration in the hydrogenated sample s, a new Broad Luminescence Band (BLB) centered at about 1.32 eV appea rs upon laser irradiation during PL experiments above 50 K, and satura tes for large values of the light intensities. It is inferred that the plasma treatment produces some kind of non-radiative defects which ca n then rearrange into new BLB centers under illumination provided it i s applied above a threshold temperature (50 K). This mechanism is inte rpreted in terms of Recombination-Enhanced Defect Reaction (REDR) invo lving the two kinds of photogenerated carriers and appears to be low t hermally assisted. The BLB is associated with the radiative emission a t a phosphorus vacancy (V-p) close to a Zn acceptor (Vp+Znln-). It is believed that the formation of BLB centers originates from V-P-related defects initially present in the freshly plasma-treated InP sample. T he mechanisms involved in the Light-Induced Creation (LIC) of BLB cent ers are discussed.