Self-biased boron-10 coated high-purity epitaxial GaAs thermal neutron detectors

Semiconductor thermal neutron detection devices based on ¹⁰ B-coated high-purity GaAs films were investigated. The fundamental device consisted of high-purity ν-type epitaxial GaAs films grown onto n-type GaAs substrates. Two blocking contact adaptations were applied to the high-purity ν-type GaAs regions: 2000 Å thick p+GaAs blocking contacts and 200 Å thick Schottky blocking contacts. The ν-type GaAs active layers ranged between 1 micron and 5 microns in thickness. The device sensitive areas were 3 mm×3 mm, each of which was coated with a 1.5 mm diameter film of 98% enriched high-purity ¹⁰B. The built-in potential of the blocking contact interface was sufficient to operate the devices, and no external voltage bias was necessary to operate the detectors. Preliminary calculations on intrinsic detection efficiency indicate values between 1.6% and 2.6%