Thick Amorphous Silicon Layers Suitable for the Realization of Radiation Detectors

Thick silicon films with good electronic quality have been prepared by glow discharge of He-diluted SiH4 at a substrate temperature approx. 150°C and subsequent annealing at 160°C for about 100 hours. The stress in the films obtained this way decreased to approx. 100 MPa compared to the 350 MPa in conventional a-Si:H. The post-annealing helped to reduce the ionized dangling bond density from 2.5 × 1015 cmˉ³ to 7 × 1014 cmˉ³ without changing the internal stress. IR spectroscopy and hydrogen effusion measurements implied the existence of microvoids and tiny crystallites in the material showing satisfactory electronic properties. P-I-N diodes for radiation detection applications have been realized out of the new material