Uncapped and Si3N4-capped annealing of GaAs grown with the horizontal Bridgman technique was investigated with deep-level transient spectroscopy. Electron trap concentration distributions were measured with a reduced noise DLTS system to ensure reliable data. Ion implantation using Se ions both prior to capping and through a Si3N4 cap was carried out. The evolution of defect energy levels and the changes in concentration distributions with anneal temperature were studied. It is concluded that the defects residing in the probed space-charge region can be annealed out with a Si3N4 cap at a temperature higher than 750 C.
