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Proceedings Paper

Investigation on origin of Ru-induced deep-level defects in 4H-SiC epilayer based Schottky diodes by DLTS and theoretical calculations
Author(s): Joshua W. Kleppinger; Yuriy Pershin; Zsolt Rak; Krishna C. Mandal
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Paper 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 Ec – (0.89 ± 0.03) eV and Ec - (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 Ev + 1.23 eV respectively.

Paper Details

Date Published: 9 September 2019
PDF: 11 pages
Proc. SPIE 11114, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXI, 111140T (9 September 2019); doi: 10.1117/12.2530177
Show Author Affiliations
Joshua W. Kleppinger, Univ. of South Carolina (United States)
Yuriy Pershin, Univ. of South Carolina (United States)
Zsolt Rak, North Carolina State Univ. (United States)
Krishna C. Mandal, Univ. of South Carolina (United States)

Published in SPIE Proceedings Vol. 11114:
Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXI
Ralph B. James; Arnold Burger; Stephen A. Payne, Editor(s)

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