DIFFUSION FORMATION OF THE i REGION IN Si(Li) DETECTORS OF NUCLEAR RADIATION

摘要

The most time-consuming and energy-intensive process in the technology of Si(Li) nuclear radiation detectors is the formation of the i region by the method of lithium ion drift. For example, months are needed to produce a 2-mm thick sensitive region of a detector. The present article describes a non-drift method of fabricating Si(Li) detectors with an extended sensitive region. To fabricate a detector based on p-type silicon, lithium ions are introduced by the method of thermal diffusion in the range 200-450℃ taking account of the fact that the redistribution of the acceptors over the entire volume of the crystal ensures their compensation. To accelerate the compensation of the i region, the lithium ions are allowed to diffuse simultaneously from two opposite end faces of the crystal surfaces [1]. The lithium ion density in the detector is established taking account of the density of acceptors and traps in the initial material. In this manner, the long-time and complex process of lithium ion drift in an electric field is replaced with diffusion annealing at temperatures from 200 to 450℃.