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“Thick” a-Si:H P-i-n diodes, produced by the VHF-GD process: spectral response for visible/infrared light and current transients

Published online by Cambridge University Press:  16 February 2011

P. Chabloz
Affiliation:
Laboratoire commun de Microtechnique, Université de Neuchâtel et Ecole Polytechnique Fédérale de Lausanne (EPFL), Breguet 2, CH-2000 Neuchâtel, Switzerland
H. Keppner
Affiliation:
Laboratoire commun de Microtechnique, Université de Neuchâtel et Ecole Polytechnique Fédérale de Lausanne (EPFL), Breguet 2, CH-2000 Neuchâtel, Switzerland
D. Fischer
Affiliation:
Laboratoire commun de Microtechnique, Université de Neuchâtel et Ecole Polytechnique Fédérale de Lausanne (EPFL), Breguet 2, CH-2000 Neuchâtel, Switzerland
N. Wyrsch
Affiliation:
Laboratoire commun de Microtechnique, Université de Neuchâtel et Ecole Polytechnique Fédérale de Lausanne (EPFL), Breguet 2, CH-2000 Neuchâtel, Switzerland
A. Shah
Affiliation:
Laboratoire commun de Microtechnique, Université de Neuchâtel et Ecole Polytechnique Fédérale de Lausanne (EPFL), Breguet 2, CH-2000 Neuchâtel, Switzerland
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Abstract

With the possibility to deposit thick amorphous silicon layers, applications like particle- or X-ray detectors can be envisaged. The present paper describes new results obtained with a series of thick p-i-n diodes produced by VHF-GD (Very High Frequency Glow-Discharge). The goal is to obtain the maximum output signal for given detection conditions (reverse voltage, generation rate,…). The problem of the collection of the electrons and holes is discussed in this paper, in relation with the distribution of the electric field. As is well known, trapped charges screen the inner part of the intrinsic layer of the detector. Due to this effect, even under strong reverse bias-voltage, a complete depletion of the whole intrinsic layer can in general not be obtained for thick diodes; however, even if the diode is not completely depleted, the signal increases with increasing diode thickness until a maximum is reached for the signal, and then it decreases again. Finally, different rise-times of the transient current (current after a jump in bias voltage is applied) have been Measured. Differing between one diode and the other, the rise-time of the transient current was found to vary between 0.1 seconds and 1 hour; a clear dependence on the deposition conditions is observed. Long rise-times are major difficulty to be removed, because most of the applications like imaging require short response time of the detector.

Type
Research Article
Copyright
Copyright © Materials Research Society 1994

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References

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