Abstract: Apparatus for semi-sealed diffusion of semiconductor materials includes a quartz tube with a quartz stopper at one end to facilitate the loading and unloading of semiconductor materials, the other end of the quartz tube having an inlet passage with a quartz stopcock. The stopper includes quartz pressure release valve.The process involves loading semiconductor material to be diffused into the tube with a source of diffusion. The semiconductor material, e.g., in the form of wafers, is first coated with an oxide layer. The stopper is inserted to seal the tube, the interiors being then purged with an inert gas supplied to the inlet passage which is subsequently closed prior to placing the tube in a furnace to initiate the diffusion process. After diffusion, the ampoule is quenched, the stopper removed and the tube unloaded. The oxide layer is then stripped off revealing a diffused, damage-free surface.