Hydrogen concentration and distribution in high-purity germanium crystals

High-purity germanium crystals used for making nuclear radiation detectors are usually grown in a hydrogen ambient from a melt contained in a high-purity silica crucible. The benefits and problems encountered in using a hydrogen ambient are reviewed. A hydrogen concentration of about 2 x 10/sup 15/cm/sup -3/ has been determined by growing crystals in hydrogen spiked with tritium and counting the tritium ..beta..-decays in detectors made from these crystals. Annealing studies show that the hydrogen is strongly bound, either to defects or as H/sub 2/ with a dissociation energy > 3 eV. This is lowered to 1.8 eV when copper is present. Etching defects in dislocation-free crystals grown in hydrogen have been found by etch stripping to have a density of about 1 x 10/sup 7/ cm/sup -3/ and are estimated to contain 10/sup 8/ H atoms each