Abstract: N-type c-BN is a heat-resistant material with a wide band gap. Ohmic electrodes are indispensable for making semiconductor devices utilizing n-type c-BN. The electrodes proposed so far are likely to deteriorate in an atmosphere of high temperature. The degradation of electrodes hinders the production of semiconductor devices utilizing c-BN. A heat-resistant ohmic electrode is produced by forming a low contact resistance layer of a boride or a nitride of Ti, Zr or Hf on a heated c-BN and by covering the low resistance layer by an Au layer. Otherwise an ohmic electrode is produced by forming a low contact resistance layer of one of Ti, Zr, Hf, etc. on c-BN, making a diffusion barrier layer of W, Mo, Ta or Pt and depositing an Au layer on the diffusion barrier layer.

Abstract: A semiconductor heterojunction structure comprising a p-type diamond layer and an n-type cubic boron nitride layer on a surface of said p-type diamond layer. Such heterojunction structure is useful for a semiconductor device such as a diode, a transistor, a laser and a rectifier, particularly an element which emits light from blue light to ultraviolet light.

Abstract: An ohmic contact electrode formed on an n-type semiconductor cubic boron nitride by using a IVa metal or an alloy with a IVa metal or a layer of Au or Ag.

Abstract: A semiconductor device having an MISFET-like structure. The semiconductor device comprises: an p-type semiconductor diamond layer disposed on an insulating diamond substrate for providing a channel region; and a drain electrode, a source electrode and a gate electrode disposed on the p-type diamond layer. An intermediate region comprising diamond doped with at least an n-type dopant such as nitrogen atoms, is formed between the channel region and the gate electrode.

Abstract: There can be provided a novel and useful process for the synthesis of hard boron nitride consisting essentially of single phase cubic boron nitride by a gaseous phase synthesis technique, which comprises adding a F atom-containing gas to the gaseous phase or adding a F atom-containing gas and H atom-containing gas to the gaseous phase, whereby the codeposited hexagonal boron nitride can selectively be etched and hard boron nitride of substantially single phase can finally be synthesized.

Abstract: A semiconductor device utilizing a non-doped diamond layer between a substrate and an active diamond layer. Such a structure decreases the resistivity and increases the carrier density. Further, when contacts are formed on the active layer, this layer structure reduces reverse leak current.

Abstract: An ohmic contact electrode is formed on an n-type semiconductor cubic boron nitride by using a IVB metal; an alloy with a IVB metal; a metal with Si or S; an alloy with Si or S; a metal with B, Al, Ga, or In; an alloy with B, Al, Ga, or In; a VB metal; or an alloy with a VB metal.

Abstract: An ohmic contact electrode formed on an n-type semiconductor cubic boron nitride by using a IVa metal; an alloy with a IVa metal; a metal with Si or S; an alloy with Si or S; a metal with B, Al, Ga, or In; an alloy with B, Al, Ga, or In; a Va metal; or an alloy with a Va metal.

Abstract: A heating process for producing a high quality diamond or c-BN film on a diamond or c-BN substrate comprising placing a diamond or c-BN substrate in vacuum, elevating the temperature and treating its surface with a chlorine containing gas, a fluorine containing gas, a nitrogen containing plasma or a hydrogen containing plasma. The treatment gas is then removed and feed gases are introduced which are suitable for growing a thin diamond or c-BN film on the surface substrate under chemical vapor deposition conditions.

Abstract: In an ohmic contact electrode for the p-type semiconductor diamond, the electrode is formed of metals or metallic compounds containing boron on a p-type semiconductor diamond, so as to obtain a decreased contact resistance.

Abstract: A semiconductor device utilizing a nondoped diamond layer between a substrate and an active diamond layer. Such a structure decreases the resistivity and increases the carrier density. Further, when contacts are formed on the active layer, this layer structure reduces reverse leak current.

Abstract: A semiconductor heterojunction structure comprising a p-type diamond layer and an n-type cubic boron nitride layer on a surface of said p-type diamond layer. Such heterojunction structure is useful for a semiconductor device such as a diode, a transistor, a laser and a rectifier, particularly an element which emits light from blue light to ultraviolet light.

Abstract: As electrodes for the semiconductor diamond, the p.sup.+ or n.sup.+ polycrystalline silicon film or amorphous silicon film including microcrystalline silicon phase is formed on the semiconductor diamond, whereby an ohmic contact electrode with low contact resistance can be made.