Carrier Lifetime Dependence on Temperature and Proton Irradiation in 4H-SiC Device: An Experimental Law

Abstract

The study focuses on analysing the high-level carrier lifetime (τHL) in 4H silicon carbide (4H-SiC) PiN diodes under varying temperatures and proton implantation doses. The objective is to identify an empirical law applicable in technology computer-aided design (TCAD) modelling for SiC devices, describing the dependence of carrier lifetime on temperature to gain insights into how irradiation dose may influence the τHL. We electrically characterize diodes of different diameters subjected to different proton irradiation doses and examine the variations in current-voltage (I-V) and ideality factor (n) curves under various irradiation conditions. The effects of proton irradiation on the epitaxial layer are analysed through capacitance-voltage (C-V) measurements. We correlate the observed effects on I-V, n, and C-V curves to the hypothesis of formation of acceptor-type defects related to carbon vacancies, specifically the Z1/2 defects generated during the irradiation process. The impact of irradiation on carrier lifetime is investigated by measuring τHL using the open circuit voltage decay (OCVD) technique at different temperatures on diodes exposed to various H + irradiation doses with constant ion energy. This investigation reveals the presence of a proportional relationship between 1/τHL and the dose of irradiated protons: the proportionality coefficient, referred to as the damage coefficient (KT), exhibits an Arrhenius-type dependence on temperature. OCVD-measured lifetime on the various diodes demonstrates a power-law dependence of lifetime on temperature. The exponent of this dependence varies with the irradiation dose, notably showing an increase in temperature dependence at the highest H + ion dose. This suggests a threshold-like dependence on H + irradiation dose in the τHLtemperature relationship.