Hydrogenated Amorphous Silicon Charge-Selective Contact Devices on a Polyimide Flexible Substrate for Dosimetry and Beam Flux Measurements.

Abstract

Hydrogenated amorphous silicon (a-Si:H) devices on flexible substrates are currently being studied for application in dosimetry and beam flux measurements. The necessity of in vivo dosimetry requires thin devices with maximal transparency and flexibility. For this reason, a thin (<10 µm) a-Si:H device deposited on a thin polyimide sheet is a very valid option for this application. Furthermore, a-Si:H is a material that has an intrinsically high radiation hardness. In order to develop these devices, the HASPIDE (Hydrogenated Amorphous Silicon Pixel Detectors) collaboration has implemented two different device configurations: n-i-p type diodes and charge-selective contact devices.Charge-selective contact-based devices have been studied for solar cell applications and, recently, the above-mentioned collaboration has tested these devices for X-ray dose measurements. In this paper, the HASPIDE collaboration has studied the X-ray and proton response of charge-selective contact devices deposited on Polyimide. The linearity of the photocurrent response to X-ray versus dose-rate has been assessed at various bias voltages. The sensitivity to protons has also been studied at various bias voltages and the wide range linearity has been tested for fluxes in the range from 8.3 × 10⁷ to 2.49 × 10¹⁰ p/(cm² s).