Electrical characterization of p-type cubic boron nitride/n-type silicon heterojunction diodes

Nanocrystalline p-type cubic boron nitride/n-type silicon diodes with three different interfaces were fabricated by plasma chemical vapor deposition and ultrahigh-vacuum bias sputter deposition. When the interface contained a t-BN layer of 25 nm thickness or less, rectification ratios as high as 4×104 at room temperature and 10 at 570 K were observed. Even when the interface contained a 1-2-nm-thick insulating layer, diode characteristics were also observed but with a lower rectification ratio of 5×102. The carrier conduction at the interface was characterized primarily by thermal excitation, where barrier height altered with bias voltage similar to the case of an ideal n-Si/p-c-BN heterojunction in the temperature range of 300-570 K.