Charged Particle Detectors Based on High Quality Amorphous Silicon Deposited with Hydrogen or Helium Dilution of Silane


Electrical transport properties of our PECVD a-Si:H material has been improved by using hydrogen and/or helium dilution of silane and lower substrate temperature for deposition. For hydrogen-diluted material we have measured electron and hole mobilities ~4 times larger, and μτ values 2-3 times higher than for our standard a-Si:H. The density of ionized dangling bonds (N[subscript D]) also showed a factor of 5-10 improvement. Due to its higher conductivity, the improved a-Si:H material is more suitable than conventional a-Si:H for TFT applications. However, it is difficult to make thick layers by H-dilution because of high internal stress. On the other hand, thick detectors can be made at a faster rate and lower stress by low temperature deposition with He-dilution and subsequent annealing. The internal stress, which causes substrate bending and delamination, was reduced by a factor of 4 to ~90 MPa, while the electronic quality was kept as good as that of the standard material. By this technique 35 µm-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.

Meeting Name

Proceedings of the 1994 Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)


Mining and Nuclear Engineering

Document Type

Article - Conference proceedings

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© 1995 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.