HEAT-TREATMENT OF AMORPHOUS AND POLYCRYSTALLINE SILICON THIN-FILMS WITH H2O VAPOR

Changes in electrical and optical properties induced by heat treatment with H2O vapor at 350 degrees C are reported for laser-induced amorph ous silicon, low pressure chemical vapor amorphous silicon (LPCVD a-Si ) and laser crystallized polycrystalline silicon films. The dark condu ctivity was reduced and the photoconductivity was increased by the hea l treatment for these Films. The optical absorption in the photon ener gy range lower than 1.5 eV was reduced for the a-Si films. The optical band gap was slightly increased from 1.48 eV to 1.51 eV for the LPCVD a-Si. The increase in hydrogen concentration was less than 2 x 10(20) cm(-3) after the treatment. These results show that the heal treatmen t with H2O vapor reduces the defect density in the silicon films with a small amount of hydrogen incorporation.