Dr. Sandeep K. Chaudhuri Profile

Dr. Sandeep K. Chaudhuri

Post-doctoral fellow at Univ of South Carolina

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Author

Publications (13)

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

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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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 August 2021 Poster

Investigation of resolution limiting traps in single-crystalline CVD diamond radiation detector using DFT calculations

Sandeep Chaudhuri, Joshua Kleppinger, Omerfaruk Karadavut, Krishna Mandal

Proceedings Volume 11838, 118381G (2021) https://doi.org/10.1117/12.2596468

KEYWORDS: Sensors, Diamond, Electrons, Chemical vapor deposition, Ultrafast phenomena, Synchrotrons, Spectroscopy, Picosecond phenomena, Particles, Nitrogen

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Proceedings Article | 24 August 2020 Presentation + Paper

Thick 4H-SiC epitaxial detectors for high-resolution radiation detection in harsh environment

Joshua Kleppinger, Sandeep Chaudhuri, Krishna Mandal

Proceedings Volume 11494, 114940X (2020) https://doi.org/10.1117/12.2570594

KEYWORDS: Sensors, Silicon carbide, Particles, Spectroscopy, Ionizing radiation, Gamma radiation

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We report on the fabrication and characterization of a high-resolution Schottky barrier radiation detector for high temperature (HT) applications using high quality 150 𝜇m thick n-4H-SiC epitaxial layers with an ultra-low micropipe density of ≤0.1 cm^-2. To evaluate the depletion region parameters of the detector, it was first characterized temperature- dependent capacitance voltage (C-V-T) measurements which showed barrier heights Φ_𝐵 ranging from 2.09 to 2.24 eV and a carrier concentration of ~2 x 10¹⁴ cm^-3 at room temperature (RT) which linearly increased at a rate of 9.65 x 1010 cm^-3/K. From the depletion region simulation studies, it was shown that the change in doping concentration with temperature (T) can increase the needed bias to fully capture charged particles by up to 9V for ²⁴¹Am and over 30V for a higher energy particles from ²¹³Po. To examine the barrier properties and leakage currents of the detectors, we have systematically characterized temperature-dependent current - voltage measurements (I-V-T). The forward bias characteristics showed two linear regions - a low voltage region corresponding to a Shockley-Read-Hall (SRH) recombination center at 𝐸_𝐶 − 0.93 eV and an upper region which corresponded to the barrier height of 2.02 eV. The reverse bias leakage currents were measured to be ~6 pA at ~65V at 300K implying a high signal to noise ratio (SNR) at RT and exhibited a current of less than 1 nA until 500K suggesting that detector should be operable with high SNR at ~200 ^oC. The Arrhenius plot of the reverse I-V-T showed an activation energy of 0.11 eV up to 400K and then 0.73 eV for 450K to 600K suggesting that most of the excess current at HT is derived from deep level state Z_1/2 recombination center. Deep level transient spectroscopy (DLTS) results showed low defect concentrations of ~1011 cm^-3 confirming that charge loss from trapping is negligible. Density functional theory (DFT) calculations suggested that the measured trap levels corresponded primarily to carbon (C) vacancies while the level at 0.93 eV corresponded to Si vacancies near the surface. The pulse height spectra (PHS) of the detector showed an excellent RT energy resolution of 0.55% FWHM at 5486 keV alpha particles after gaussian correction owed gamma response at 59.54 keV.

Proceedings Article | 20 August 2020 Poster + Presentation + Paper

Investigation on Cd0.9Zn0.1Te1-ySey single crystals grown by vertical Bridgman technique for high-energy gamma radiation detectors

Mohsin Sajjad, Sandeep Chaudhuri, Joshua Kleppinger, OmerFaruk Karadavut, Krishna Mandal

Proceedings Volume 11494, 114941F (2020) https://doi.org/10.1117/12.2570592

KEYWORDS: Sensors, Crystals, Tellurium, Zinc, Electrons, Cadmium, Gamma radiation, Selenium, Spectroscopy

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Proceedings Article | 9 September 2014 Paper

Investigation of low leakage current radiation detectors on n-type 4H-SiC epitaxial layers

Khai Nguyen, Sandeep Chaudhuri, Krishna Mandal

Proceedings Volume 9213, 921315 (2014) https://doi.org/10.1117/12.2063055

KEYWORDS: Sensors, Silicon carbide, Silica, Silicon, Plasma enhanced chemical vapor deposition, Spectroscopy, Capacitance, Semiconducting wafers, Dielectrics, Sensor performance

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