A high voltage computer controlled experimental system for the investigation of amorphous semiconductors as image sensors

This paper describes an ongoing programme of work designed to investigate dark discharge and photoconductivity in amorphous semiconductors with a view to applying these materials to industrial optical process tomography (OPT). Extensive laboratory equipment has been developed to investigate the aforementioned phenomena in amorphous arsenic triselenide (a-As2Se3) and hydrogenated amorphous silicon (a-Si: H). Photoconductivity measurements are performed in both xerographic and electroded modes by the use of a purpose built xenon ‘ash facility which can deliver pulsed light of user defined intensity, duration, and frequency. Control of the laboratory apparatus and the collection of data is fully automated, and the laboratory apparatus conforms to all relevant health and safety regulations concerning working with high voltages. Extensive software has been written for the data handling, data management, data display and numerical analysis of the experimental data. The advantages of amorphous semiconductors for OPT are discussed in section 1. Section 2 contains an overview of the developed experimental apparatus, and finally, section 3 brie‘y describes the amorphous semiconductor material’s ability to produce qualitative and quantitative data for imaging or control signal generation.