Ultraviolet triggering and characterization of diamond photoconductive semiconductor switches for advanced high-power, high-speed applications
Mazumder, Anik
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https://hdl.handle.net/2142/129165
Description
Title
Ultraviolet triggering and characterization of diamond photoconductive semiconductor switches for advanced high-power, high-speed applications
Author(s)
Mazumder, Anik
Issue Date
2025-05-05
Director of Research (if dissertation) or Advisor (if thesis)
Eden, James Gary
Department of Study
Electrical & Computer Eng
Discipline
Electrical & Computer Engr
Degree Granting Institution
University of Illinois Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Keyword(s)
PCSS
Diamond
Ultra-wide Bandgap
Intrinsic
Microplasma Lamps
DUV, VUV
Responsivity
etc.
Language
eng
Abstract
Diamond photoconductive semiconductor switches (PCSS) are becoming very popular because of their high critical electric field strength, superior thermal conductivity, and fast switching speed. In this work, the performance of intrinsic lateral diamond PCSS devices is investigated, with a focus on developing both coherent and incoherent optical triggering, and also correlating device characteristics with background impurity concentrations. The switches are first triggered using ultraviolet (UV) laser excitation in the 212-240 nm range, covering both the near- and above-bandgap photon energies. The laser optical triggering system is optimized for a spatially uniform beam over the devices’ active area without significant energy attenuation and ensuring wide-range pulse energy tuning. For space- and cost-effectiveness, the devices are also tested with different microplasma UV lamps instead of the laser. Although the lamp-triggered photocurrent is three orders of magnitude lower than that of the laser-triggering, this paves the path for compact high-voltage packaging and triggering of PCSS for commercial applications. The device endurance for high-power applications is investigated at applied DC biases between –1.2 kV and +1.2 kV. All devices exhibit fast rise times under 3 ns, limited primarily by the rise time of the excitation laser. The fall time varies with the impurity concentration, and the carrier lifetime decreases with higher impurity concentrations, leading to fast device turn-off. Among the tested lateral devices, the switch fabricated on the substrate with the lowest impurity concentration demonstrates the best performance in terms of the peak photocurrent, responsivity, and on/off ratio. Nevertheless, a trade-off emerges where higher levels of natural impurities facilitate faster fall times but compromise current output.
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