Accession Number:

ADA609481

Title:

Monte Carlo Evaluation of Tritium Beta Spectrum Energy Deposition in Gallium Nitride (GaN) Direct Energy Conversion Devices

Descriptive Note:

Final rept. Jan-Jul 2014

Corporate Author:

ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE

Personal Author(s):

Report Date:

2014-09-01

Pagination or Media Count:

22.0

Abstract:

In this report, a Monte Carlo nuclear scattering code Monte Carlo n-particle extended MCNPX was used to investigate the possibility of using gallium nitride GaN semiconductors for the purpose of converting the low energy emitted during natural decay of tritium 3H into electrical current for use in a power source. The shape of the beta decay spectrum differs in isotopes because of screening potentials and forbidden transitions. Therefore the use of average energy or endpoint energy is not sufficient for a detailed understanding of energy deposition in a material. The technique of direct energy conversion DEC is considered advantageous with GaN compared to that of silicon carbide SiC. GaN has a direct band gap material of 3.4 eV compared to the more commonly used SiC with a 3.2-eV indirect band gap. The beta emission spectrum from 3H, directed toward a GaN converter is modeled. A GaN device optimized to stop all in 3H would be less than 1.5 m thick. The depletion region in a GaN DEC that would enclose 99 of the charge generated by separated electron hole pairs is calculated to be 700 nm thick for 3H.

Subject Categories:

  • Inorganic Chemistry
  • Non-electrical Energy Conversion
  • Statistics and Probability

Distribution Statement:

APPROVED FOR PUBLIC RELEASE