Silicon avalanche photodiodes for particle detector:: modelling and fabrication

Large-area arrays (30×30) of metal/resistive layer/silicon (MRS) avalanche photodiodes as 150×150 μm sub-pixels were developed and fabricated to detect short-wavelength scintillator signals for high-energy particle detection. Modelling of MRS photodiodes was performed using McIntyreʹs approach of local electric field to optimize semiconductor doping profiles and resistive layer parameters and to obtain the minimum value of effective k-factor (the holes to electrons ionization coefficients ratio) less than 0.01 under low excess noise factor and high gain. The resistive layer/silicon surface barrier suppresses minority carriers injection to decrease dark current and effective k-factor. Test samples of silicon avalanche photodiodes arrays have been fabricated using low-rate epitaxial growth of silicon layer, impurity doping, and resistive layer deposition processing. The integral gain for experimental specimens was ∼100.