4H-SiC Schottky diode radiation hardness assessment by IBIC microscopy

TL;DR

This study uses IBIC microscopy to analyze how 4H-SiC Schottky diodes' charge collection efficiency and depletion layer are affected by high-energy C ion irradiation, revealing defect-induced electrostatic changes.

Contribution

It provides new insights into radiation-induced defect effects on 4H-SiC Schottky diodes using IBIC microscopy and electrostatic modeling.

Findings

Depletion layer widens with bias in pristine diodes.

C ion irradiation causes depletion layer shrinkage.

Defects with positive charge state perturb electrostatic landscape.

Abstract

We report findings on the Ion Beam Induced Charge (IBIC) characterization of a 4H-SiC Schottky barrier diode (SBD), in terms of the modification of the Charge Collection Efficiency (CCE) distribution induced by 20 MeV C ions irradiations with fluences ranging from 20 to 200 ions/um2. The lateral IBIC microscopy with 4 MeV protons over the SBD cross section, carried out on the pristine diode evidenced the widening of the depletion layer extension as function of the applied bias and allowed the measurement of the minority carrier diffusion lengths. After the irradiation with C ions, lateral IBIC showed a significant modification of the CCE distribution, with a progressive shrinkage of the depletion layer as the fluence of the damaging C ions increases. A simple electrostatic model ruled out that the shrinkage is due to the implanted charge and ascribed the perturbation of the electrostatic landscape to radiation-induced defects with positive charge state.