Junction Properties of Polycrystalline Diamond/Hydrogenated Amorphous Silicon p-n Heterojunctions

Junction properties of polycrystalline diamond have been studied using heterojunctions between p-type polycrystalline diamond and n-type hydrogenated amorphous silicon (a-Si:H). For the range of resistivity of polycrystalline diamond from 1 Ω cm to 120 Ω cm, current-voltage (I-V) characteristics of the p-n heterojunctions show a distinct rectification and capacitance-voltage (C-V) characteristics show an approximately linear C -2-V relationship in the reverse bias condition, indicating that the depletion layer occurs in the vicinity of the junction in the same manner as for the conventional crystalline p-n heterojunction. The temperature dependences of I-V and C-V characteristics are described by the conventional heterojunction models proposed for the crystalline semiconductors. These results suggest that junction properties of polycrystalline diamond are not greatly influenced by features of the polycrystalline film, such as grain boundaries and roughness of the surface, although these seem to affect the carrier transport in the polycrystalline network.