Mr. Ritwik Nag Profile

Ritwik Nag

at Univ of South Carolina

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Publications (5)

Proceedings Article | 4 October 2023 Presentation

Correlation of transport properties with charge trapping parameters in Cd0.9Zn0.1Te1-xSex room temperature gamma-ray detectors

Ritwik Nag, Sandeep Chaudhuri, Krishna Mandal

Proceedings Volume PC12696, PC1269604 (2023) https://doi.org/10.1117/12.2682618

KEYWORDS: Crystals, Gamma radiation, Spectroscopy, Imaging spectroscopy, Temperature metrology, Selenium, Matrices, Compound semiconductors

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Proceedings Article | 4 October 2022 Presentation + Paper

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

OmerFaruk Karadavut, Ritwik Nag, Josh Kleppinger, Gene Yang, Dongkyu Lee, Sandeep Chaudhuri, Krishna Mandal

Proceedings Volume 12241, 1224107 (2022) https://doi.org/10.1117/12.2635949

KEYWORDS: Sensors, Silicon carbide, Capacitance, Dielectrics, Oxides

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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.

Proceedings Article | 1 September 2021 Presentation + Paper

High-resolution 4H-SiC Schottky barrier radiation detectors on 250 micron epitaxial layers for harsh environment applications

Joshua Kleppinger, Omerfaruk Karadavut, Ritwik Nag, Sandeep Chaudhuri, Krishna Mandal

Proceedings Volume 11838, 1183816 (2021) https://doi.org/10.1117/12.2596470

KEYWORDS: Sensors, Silicon carbide, Capacitance, Diffusion, Semiconductors, Environmental sensing, Defect detection, Nuclear radiation detection

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Proceedings Article | 1 September 2021 Presentation + Paper

Observation of minority carrier traps using C-DLTS in Au/SiO2/n-4H-SiC vertical MOS capacitor

Omerfaruk Karadavut, Joshua Kleppinger, Ritwik Nag, Sandeep Chaudhuri, Krishna Mandal

Proceedings Volume 11838, 1183815 (2021) https://doi.org/10.1117/12.2596464

KEYWORDS: Nuclear radiation detection, Defect detection, Sensors, Silicon carbide

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Proceedings Article | 1 September 2021 Presentation + Paper

A CdZnTeSe gamma spectrometer trained by deep convolutional neural network for radioisotope identification

Sandeep Chaudhuri, Joshua Kleppinger, Ritwik Nag, Kaushik Roy, Rojina Panta, Forest Agostinelli, Amit Sheth, Utpal Roy, Ralph James, Krishna Mandal

Proceedings Volume 11838, 1183806 (2021) https://doi.org/10.1117/12.2596456

KEYWORDS: Nuclear radiation detection, Sensors, Gamma radiation, Spectroscopy, Monte Carlo methods, Convolutional neural networks, Neural networks, Compton scattering

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