The formation of ohmic Au/Mo/Ti contacts to epitaxial p-type diamond films is studied. The effect of annealing on the electrical and structural properties of contacts has been investigated. It was shown that during rapid thermal annealing, the outer layer of gold protects the contact system from oxidation up to a temperature of 850°C, unlike the simplified Au/Ti system, which is more common in modern works. In Au/Ti structures without a Mo layer after high-temperature annealing, effective diffusion of titanium into the gold layer occurs, which reduces its protective properties and accelerates the diffusion of oxygen to the boundary with the diamond. Oxidation of the Ti/C contact region blocks the formation of a conductive layer of titanium carbide with high adhesion at the border with diamond. The role of various factors in reducing the contact resistance is compared: annealing for the formation of titanium carbide, heavy doping of diamond with boron atoms, and crystalline perfection of epitaxial diamond substrates. For doped epitaxial films grown on single-sector quality substrates, non-annealed ohmic contacts with a record contact resistance of 4•10<-7> Ω•cm<2> were obtained.

Undoped nanocrystalline diamond (NCD) films less than 1 μm thick grown on Si (100) silicon by microwave plasma-assisted chemical vapor deposition at a frequency of 2.45 GHz are studied. To obtain diamond dielectric films with maximum resistivity the deposition of films in three gas mixtures is investigated: hydrogen-methane mixture, hydrogen-methane mixture with the addition of oxygen and hydrogen-methane mixture with the addition of an inert gas. A relationship has been established between the growth conditions, structural and electrical properties of NCD films. It is shown that for the use of NCD films as effective dielectrics preliminary high-temperature annealing of the films is required, for example, in vacuum at a temperature of 600°C for one hour.

Various methods of the formation of ohmic contacts to CVD diamond epitaxial structures with boron doped delta layers (δ-layers) are investigated. In the first approach, an additional thin, heavily doped layer was formed on the surface of the diamond film, to which the ohmic contact was formed. Then, the surface p+-layer between the contact pads was etched out, so the current flow in the structure occurred only through the buried δ-layer. In the second approach, doped diamond was selectively grown in contact windows under the mask of metal after preliminary etching the undoped diamond layer (cap) to the δ-layer. In this case, the heavily doped p+-layer will form a contact to the δ-layer. These approaches are differs by conditions of applicability, the complexity of manufacturing technology, the value of contact resistance. So they can be used to solve tasks in which different quality of contacts is required, such as the formation of transistor structures or test cells for measuring electrophysical characteristics.

The effect of pulsed laser annealing on the formation of ohmic Mo/Ti contacts to diamond is studied. Using the method of secondary-ion mass spectrometry, it was shown that laser annealing of the contacts leads to effective diffusion of carbon atoms into the titanium layer and the formation of titanium carbide in the transition region with a diamond with a thickness of 15-20 nm. Rapid thermal annealing of the same contact system is accompanied by a sharp increase in the oxygen content in the titanium layer and in the transition layer with diamond and the formation of titanium oxide. In this case, the titanium carbide phase is not formed in the Ti-C transition layer. It was also shown that, in the used laser annealing mode, graphitization of the contact layer of diamond does not occur, which could drastically reduce the mechanical strength and adhesion of the contacts.

The influence of thermal annealing on the transport properties of Ti/AlGaN/GaN low-barrier Mott diodes with near-surface polarization-induced δ-doping has been studied. It is shown that annealing provides additional possibilities for controlling the effective barrier height of diodes, improving and fine-tuning their transport characteristics. Thermal annealing can be used to fabricate low-barrier diodes designed to operate at high temperatures.