Abstract
The operation dynamics of the capacitor-type and PIN diode type detectors based on GaN have been simulated using the dynamic and drift-diffusion models. The drift-diffusion current simulations have been implemented by employing the software package Synopsys TCAD Sentaurus. The monopolar and bipolar drift regimes have been analyzed by using dynamic models based on the Shockley-Ramo theorem. The carrier multiplication processes determined by impact ionization have been considered in order to compensate carrier lifetime reduction due to introduction of radiation defects into GaN detector material.
Highlights
Interpretation of transient currents in particle and photodetectors, due to drift of the injected charges, is a sophisticated issue which depends on many factors
The Sensors 2015, 15 latter approach is acceptable for simulation of quasi-steady-state regime, and, as emphasized in [11], “an analysis based on the Boltzmann equation with a rigorous treatment of the collision integral is prohibitive” in the dynamic theories concerned with the transport properties under dynamic conditions, i.e., when the electric field varies in time and space
Time-dependent variations of current may be determined by externally injected charge domain dissipation through domain drift and dielectric relaxation due to media polarization effects, through carrier capture in traps containing material, and via diffusion processes
Summary
Interpretation of transient currents in particle and photodetectors, due to drift of the injected charges, is a sophisticated issue which depends on many factors. Current density changes dependent on applied voltage can be simulated based on a system of Boltzmann equation, e.g., [10], using conservation laws for carrier concentration, momentum and energy. Radiation-induced defects are one of the most significant limiting factors for the operational characteristics of particle detectors during high fluence irradiations. GaN crystalline material of a proper quality is usually obtained by the MOCVD technique, and the as-grown epi-layers are rather thin. It has been evaluated [13,14] that carrier pair generation by high energy protons comprises efficiency of 40–80 pairs per μm length of the device active width per proton. The thermal noise current is considerably reduced in wide band-gap materials
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