Modelling of semi-conductor diodes made of high defect concentration, irradiated, high resistivity and semi-insulating material: the internal field

Full one-dimensional modelling is reported of the internal electric field in a long PIN semi-conductor diode with different concentrations of shallow- and deep-donors and acceptors and generation–recombination centres. There are considerable differences from the textbook results of defect free diodes. We present a physical understanding of the processes involved. There are specific applications of these results to radiation damaged devices and devices made from high-resistance and semi-insulating materials. The field profiles show how it is possible to construct diodes with high fields at either end of the diode or with a constant field across the length of the diode. This has considerable implication for the charge collection performance of high-energy particle detectors, which have been heavily irradiated.