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 hyd rogenated amorphous silicon (a-Si:H). For the range of resistivity of polycrystalline diamond from 1 OMEGA cm to 120 OMEGA cm, current-volta ge (I-V) characteristics of the p-n heterojunctions show a distinct re ctification and capacitance-voltage (C-V) characteristics show an appr oximately linear C-2-V relationship in the reverse bias condition, ind icating that the depletion layer occurs in the vicinity of the junctio n in the same manner as for the conventional crystalline p-n heterojun ction. The temperature dependences of I-V and C-V characteristics are described by the conventional heterojunction models proposed for the c rystalline semiconductors. These results suggest that junction propert ies 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 t he polycrystalline network.