Improved p–n heterojunction device performance induced by irradiation in amorphous boron carbide films

• Amorphous boron carbide films were grown on n-type silicon creating a heterojunction.
• We irradiated the devices with 200 keV alpha particles to varying levels of damage.
• We measured the current versus voltage at each level of damage for the device.
• The electrical properties improved with moderate amounts of irradiation.
• Device failure is due to the fragility of the Si, not the boron carbide film.

Amorphous hydrogenated boron carbide films (a-B10C2+x:Hy) on Si p–n heterojunctions were fabricated utilizing plasma enhanced chemical vapor deposition (PECVD). These devices were found to be robust when irradiated with 200 keV He+ ions. For low doses of irradiation, contrary to most other electrical devices, the electrical performance improved. On the heterojunction I(V) curve, reverse bias leakage current decreased by 3 orders of magnitude, series resistance across the device decreased by 64%, and saturation current due to generation of electron–hole pairs in the depletion region also decreased by an order of magnitude. It is believed that the improvements in the electrical properties of the devices are due to an initial passivation of defects in the a-B10C2+x:Hy film resulting from electronic energy deposition, breaking bonds and allowing them to reform in a lower energy state, or resolving distorted icosahedron anion states.