Hot Filament Chemical Vapor Deposition of Semiconducting Boron Carbide Thin Films

A highly efficient, low-power, compact thermal neutron detection system with excellent gamma-ray discrimination is desired for a number of applications. ¹⁰B [boron- 10] has a large cross section for thermal values and a Q-value of 2.78 MeV. For this reason, investigations into boron carbide, boron nitride, and boron phosphide semiconductor neutron detectors are underway. Because boron carbide has the highest fraction of boron of the three, it holds the highest potential. With this in mind, a hot filament chemical vapor deposition (HFCVD) system was designed and built in order to grow thin films of boron carbide onto n-type silicon substrates. Deposition was accomplished via the thermal decomposition of B₂H₆ [diborane] and CH₄ [methane].