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 d evice quality are made by helium dilution of the process gas and heat treatment for application to minimum ionizing particle detection. Dilu tion of SiH4 with He decreased the dangling bond density and increased the deposition rate. The internal stress, which causes substrate bend ing and delamination, was reduced by a factor of 4 to similar to 90 MP a when deposited at low (150 degrees C) temperature. The electronic qu ality of the a-Si:H film was somewhat degraded when grown at a low tem perature, 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 wit hout significant substrate bending, and the electronic properties, suc h as electron mobility and ionized dangling bond density, were suitabl e for detecting minimum ionizing particles. Diode readouts and integra ted amplifiers for pixel arrays are also described.