Amorphous Silicon–Phosphorus Layers

Abstract

EPB, photo- and dark conductivity are investigated for amorphous silicon films prepared by vacuum deposition of the silicon-phosphorus vapour mixture. It is shown that as the phosphorus vapour pressure increases (pP ≦ 10−3 Pa) the conductivity decreases and paramagnetic centres with g = 2.0055 disappear. The temperature dependence of the dark conductivity and EPR data permit the conclusion that the phosphorus doping by vacuum evaporation technique enables one to decrease the localized state density in a-Si down to 1017 cm−3 eV−1. With a further increase of pP (> 10−3 Pa) the n-type conductivity appears. The maximum value of σ is 10−3 (Ω cm)−1, though the phosphorus concentration in a-Si:P ranges from 1019 to 3 × 1022 cm−3. It is found that the a-Si: P layers are characterized by high values of photoconductivity and thermally stable when heated up to 500 °C. [Russian Text Ignored]