Design and fabrication of a Si PIN-type radiation detector for alpha spectroscopy

Silicon PIN-type radiation detectors, which have 4.5 kΩ·cm and 7 kΩ·cm resistivities, were designed and fabricated for alpha spectroscopy. The main design considerations of the Si PIN-type radiation detector were a high biasing voltage, a low leakage current, and a low alpha energy loss caused by the incident window of the p⁺ layer. Two guard electrodes and an edge protection structure were incorporated to minimize the leakage current and to apply a high bias voltage for full depletion. A shallow p⁺ layer and non-metal deposition on the p⁺ layer were also incorporated to minimize alpha energy loss. The doping profile of the p⁺ layer and the alpha energy loss due to p+ layer were approximately calculated by using a Silvaco device simulation tool kit and the SRIM code, respectively. About 7-nA reverse leakage current at a 200-V reverse bias voltage and an energy resolution a 1.1% for 5.5 MeV alpha particles were achieved with the fabricated Si PIN-type radiation detectors, which had two different resistivities. Several important aspects to consider in the fabrication of a Si PIN-type radiation detector are also addressed.