THICK (SIMILAR-TO-50-MU-M) AMORPHOUS-SILICON P-I-N-DIODES FOR DIRECT-DETECTION OF MINIMUM IONIZING PARTICLES

Thick(similar to 50 mu m) amorphous silicon (a-Si:H) p-i-n diodes of device quality are made by helium dilution of the process gas and heat treatment for application to minimum ionizing particle detection. Dilution of SiH4 with He decreased the dangling bond density and increased the deposition rate. The internal stress, which causes substrate bending and delamination, was reduced by a factor of 4 to similar to 90 MPa when deposited at low (150 degrees C) temperature. The electronic quality of the a-Si:H film was somewhat degraded when grown at a low temperature, but could be mostly recovered by subsequent annealing at 160 degrees C. By this technique 50 mu m thick n-i-p diodes were made without significant substrate bending, and the electronic properties, such as electron mobility and ionized dangling bond density, were suitable for detecting minimum ionizing particles. Diode readouts and integrated amplifiers for pixel arrays are also described.