n‐type GaAs specimens have been annealed in sealed quartz ampoules and characterized with electron‐beam‐induced current and photoresponse measurements, deep‐level transient spectroscopy, and photoluminescence spectroscopy. By correlating changes in the concentrations of defects with minority‐carrier diffusion length (Lp) it is shown that the dominant recombination center in this material is a hole trap termed HCX (Ev+0.29 eV). Increases inLpof up to a factor of 3, which can be achieved by proximity annealing at 950 °C for 16 h, are related to the loss of As from the specimen surfaces during the early stages of annealing. The beneficial effect of the annealing is associated with a limited source diffusion process since the total amount of As loss is determined by the ratio of the ampoule volume to the GaAs surface area. Proximity protection of the surfaces is necessary to prevent the generation of a Ga vacancy‐related hole trap HCZ (Ev+0.57 eV).