Investigation of Ni/Y2O3/n-4H-SiC metal-oxide-semiconductor structure for high-resolution radiation detection

OmerFaruk Karadavut; Ritwik Nag; Josh W. Kleppinger; Gene Yang; Dongkyu Lee; Sandeep K. Chaudhuri; Krishna C. Mandal

doi:10.1117/12.2635949

4 October 2022 Investigation of Ni/Y₂O₃/n-4H-SiC metal-oxide-semiconductor structure for high-resolution radiation detection

OmerFaruk Karadavut, Ritwik Nag, Josh W. Kleppinger, Gene Yang, Dongkyu Lee, Sandeep K. Chaudhuri, Krishna C. Mandal

Author Affiliations +

Proceedings Volume 12241, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXIV; 1224107 (2022) https://doi.org/10.1117/12.2635949
Event: SPIE Optical Engineering + Applications, 2022, San Diego, California, United States

Abstract

Ni/Y₂O₃/4H-SiC metal-oxide-semiconductor (MOS) structure has been realized on 20 μm thick 4H-SiC epitaxial layers by depositing 40 nm thick Y₂O₃ layers through pulsed laser deposition and using nickel as the gate contact. 4H-SiC based MOS structures with thin oxide layers are being considered as novel detector structures for ionizing radiation. Y₂O₃ being a wide bandgap (5.5 eV) and high-𝑘 dielectric (𝑘 = 14-16) is beneficial to lower the junction leakage current and increasing the bias voltage limit. The current-voltage (I-V) characteristics recorded for the fabricated MOS devices revealed excellent rectification properties and a very low leakage current density of 80 pA/cm² at a gate bias of -500 V. The Mott-Schottky plot obtained from high frequency (1 MHz) capacitance-voltage (C-V) measurement revealed a linear trend as observed in Ni/4H-SiC Schottky barrier detectors. A built-in potential of ≈2.0 V has been calculated from the C-V characteristics. The radiation detection properties of the MOS detectors have been assessed through pulse height spectroscopy using a ²⁴¹Am alpha particle source. The detectors revealed a well-defined peak in the pulse height spectrum with an energy resolution of 1.6% and a charge collection efficiency (CCE) of 82% at 0 V applied bias (self-biased mode) for the 5486 keV alpha particles. The energy resolution and the charge collection efficiency were seen to improve further with increased gate bias. A CCE of 1.0 and an energy resolution of 0.4% has been observed when the MOS detector was biased at -50 V. A very long hole diffusion length of 56 μm has been calculated using a drift-diffusion model and the variation of experimentally obtained CCE with bias voltage. Such long hole diffusion length and the high built-in potential has led to the highefficiency detection performance in self-biased mode. Capacitance-mode deep level transient spectroscopy revealed the presence of deep level trap centers commonly observed in 4H-SiC epilayers with trap concentrations similar to that has been observed in our previous devices.

Conference Presentation

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OmerFaruk Karadavut, Ritwik Nag, Josh W. Kleppinger, Gene Yang, Dongkyu Lee, Sandeep K. Chaudhuri, and Krishna C. Mandal "Investigation of Ni/Y₂O₃/n-4H-SiC metal-oxide-semiconductor structure for high-resolution radiation detection", Proc. SPIE 12241, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXIV, 1224107 (4 October 2022); https://doi.org/10.1117/12.2635949

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