IEEE Access (Jan 2024)
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 ( $\tau _{\mathrm {HL}}$ ) 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 $\tau _{\mathrm {HL}}$ . 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 Z $_{\mathrm {1/2}}$ defects generated during the irradiation process. The impact of irradiation on carrier lifetime is investigated by measuring $\tau _{\mathrm {HL}}$ 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/ $\tau _{\mathrm {HL}}$ and the dose of irradiated protons: the proportionality coefficient, referred to as the damage coefficient (K $_{\mathrm {T}}$ ), 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 $\tau _{\mathrm {HL}}$ -temperature relationship.
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