Investigation on origin of Ru-induced deep-level defects in 4H-SiC epilayer based Schottky diodes by DLTS and theoretical calculations

Joshua W. Kleppinger; Yuriy Pershin; Zsolt Rak; Krishna C. Mandal

doi:10.1117/12.2530177

9 September 2019 Investigation on origin of Ru-induced deep-level defects in 4H-SiC epilayer based Schottky diodes by DLTS and theoretical calculations

Joshua W. Kleppinger, Yuriy Pershin, Zsolt Rak, Krishna C. Mandal

Author Affiliations +

Proceedings Volume 11114, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXI; 111140T (2019) https://doi.org/10.1117/12.2530177
Event: SPIE Optical Engineering + Applications, 2019, San Diego, California, United States

Abstract

We present a dual experimental and computational studies on ruthenium (Ru) induced point defects in wide bandgap semiconductor 4H-silicon carbide (4H-SiC) which is of high interest in alpha, x-ray, and low energy gamma spectroscopy due to Ru’s high weighted metal work function of 4.76 eV which forms a high barrier Schottky contact with low leakage current. We first measured the activation energies and concentrations of deep levels in RF sputtered Ru/n-4H-SiC Schottky diodes annealed at 950°C using deep level transient spectroscopy (DLTS) and identified two deep level defects at E_c – (0.89 ± 0.03) eV and E_c - (1.98 ± 0.03) eV which appear unique to Schottky diodes with Ru. In order to correlate these defects theoretically, we then calculated the formation energies and transition levels of Ru induced point defects in 4H-SiC at charge states [-2, 2] for substitutions and [-2,+4] for interstitials using the projector augmented wave method (PAW) with both PBE and hybrid pseudopotentials on a 3 x 3 x 1 supercell. We found two transition levels which correlate very well with our experimental DLTS results. The transition (-1/0) for Ru substituted into the cubic silicon site at Ev + 2.39 eV and the transition (-1/0) for Ru placed in interstitial site with tetrahedral symmetry to carbon at E_v + 1.23 eV respectively.

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Joshua W. Kleppinger, Yuriy Pershin, Zsolt Rak, and Krishna C. Mandal "Investigation on origin of Ru-induced deep-level defects in 4H-SiC epilayer based Schottky diodes by DLTS and theoretical calculations", Proc. SPIE 11114, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXI, 111140T (9 September 2019); https://doi.org/10.1117/12.2530177

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