skip to main content

SciTech ConnectSciTech Connect

Title: High efficiency 4H-SiC betavoltaic power sources using tritium radioisotopes

Realization of an 18.6% efficient 4H-silicon carbide (4H-SiC) large area betavoltaic power source using the radioisotope tritium is reported. A 200 nm 4H-SiC P{sup +}N junction is used to collect high-energy electrons. The electron source is a titanium tritide (TiH{sup 3}{sub x}) foil, or an integrated titanium tritide region formed by the diffusion of tritium into titanium. The specific activity of the source is directly measured. Dark current measured under short circuit conditions was less than 6.1 pA/cm{sup 2}. Samples measured with an external tritium foil produced an open circuit voltage of 2.09 V, short circuit current of 75.47 nA/cm{sup 2}, fill factor of 0.86, and power efficiency of 18.6%. Samples measured with an integrated source produced power efficiencies of 12%. Simulations were done to determine the beta spectrum (modified by self absorption) exiting the source and the electron hole pair generation function in the 4H-SiC. The electron-hole pair generation function in 4H-SiC was modeled as a Gaussian distribution, and a closed form solution of the continuity equation was used to analyze the cell performance. The effective surface recombination velocity in our samples was found to be 10{sup 5}–10{sup 6 }cm/s. Our analysis demonstrated that the surface recombination dominates the performance of a tritium betavoltaic devicemore » but that using a thin P{sup +}N junction structure can mitigate some of the negative effects.« less
Authors:
;  [1] ;  [2]
  1. Widetronix Corp., Ithaca, New York 14850 (United States)
  2. Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14850 (United States)
Publication Date:
OSTI Identifier:
22499202
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 108; Journal Issue: 1; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; 07 ISOTOPES AND RADIATION SOURCES; BETA SPECTRA; BETAVOLTAIC CELLS; CONTINUITY EQUATIONS; ELECTRICAL FAULTS; ELECTRON SOURCES; FILL FACTORS; FOILS; GAUSS FUNCTION; HOLES; P-N JUNCTIONS; SELF-ABSORPTION; SILICON CARBIDES; TITANIUM; TRITIDES; TRITIUM