APPLICATION OF DIAMOND-LIKE CARBON-FILMS ON CRYSTALLINE SILICON TO HETEROJUNCTION PHOTODIODES

We studied the properties of a heterojunction photodiode fabricated from diamondlike carbon films (DLC) on p-type crystalline silicon (c-Si). DLC films were prepared by a capacitively coupled radio-frequency plasma-enhanced chemical vapor deposition technique using methane as process gas. After deposition, the samples were annealed at 250 degrees C in a high-pressure hydrogen atmosphere (300 bar) for several hours in order to reduce the interface trap density. The quantum efficiency of the heterostructure DLC/p-type c-Si (10-20 Omega cm) was substantially improved by the postdeposition treatment in a high-pressure hydrogen atmosphere. After this treatment the quantum efficiency exceeded unity indicating a charge-carrier multiplication.