Formation of singular (001) terraces on the surface of single-crystal HPHT diamond substrates

Methods of the experimental diagnostics and control of the misorientation angle for single-crystal HPHT (High Pressure High Temperature) diamond substrates are discussed. Such substrates are used for the homoepitaxial growth of doped and undoped CVD diamond layers. The formation of singular (001) terraces on the surface of HPHT diamond after microwave-discharge-plasma etching in pure hydrogen or a hydrogen–oxygen mixture is observed. This phenomenon can be used for rapid determination of the substrate misorientation and to improve the control precision of the deviation angle during substrate polishing, or for obtaining large singular (001) areas of single-crystal diamond substrates.     

Microcrystalline diamond growth in presence of argon in millimeter-wave plasma-assisted CVD reactor

The additions of argon and oxygen to H₂–CH₄ feed gas and high-electron-density plasma generated by the millimeter-wave power were used to deposit microcrystalline diamond films having high quality and high growth rate simultaneously. Microcrystalline diamond films were grown on silicon substrates with 60–90 mm diameter in the millimeter-wave plasma-assisted CVD reactor based on 10 kW gyrotron operating at a frequency of 30 GHz. The growth process and morphology of diamond films at wide variation of parameters (gas pressure, substrate temperature, microwave power, argon and oxygen concentrations in gas mixtures Ar–H₂–CH₄ and Ar–H₂–CH₄–O₂) are investigated. For understanding of growth conditions the investigations of the plasma parameters (electron density and gas temperature) in novel CVD reactor are presented.     

Characterization of single-crystal diamond grown from the vapor phase on substrates of natural diamond

The results of studies of single-crystal diamond layers with orientation (100) grown on substrates of IIa-type natural diamond by chemical-vapor deposition and of semiconductor diamond obtained subsequently by doping by implantation of boron ions are reported. Optimal conditions of postimplantation annealing of diamond that provide the hole mobility of 1150 cm² V^?1 s^?1 (the highest mobility obtained so far for semiconductor diamond after ion implantation) are given.     

Combined single-crystalline and polycrystalline CVD diamond substrates for diamond electronics

The fabrication of diamond substrates in which single-crystalline and polycrystalline CVD diamond form a single wafer, and the epitaxial growth of diamond films on such combined substrates containing polycrystalline and (100) single-crystalline CVD diamond regions are studied.     

Homoepitaxial single crystal diamond grown on natural diamond seeds (type IIa) with boron-implanted layer demonstrating the highest mobility of 1150 cm/V s at 300 K for ion-implanted diamond

The homoepitaxial single crystal diamond growth by microwave plasma assisted CVD at high microwave power density 200 W/cm³ in a 2.45 GHz MPACVD reactor using natural diamond seeds (type IIa) was investigated. The semiconductor CVD diamond of p-type was obtained by doping technique of ion implantation. Boron ions were implanted at the acceleration energy of 80 keV with two cases of dose: 5 · 10¹⁴ and 3 · 10¹⁵ cm^− 2. To recover the damage layer and activate dopants in CVD diamond the rapid annealing at nitrogen atmosphere at 1380° C was used. B-implanted diamond layer showing the mobility of 1150 cm²/V s at 300 K which is the highest for ion-implanted diamond was obtained.     

Atomic composition and electrical characteristics of epitaxial CVD diamond layers doped with boron

The results of analysis of the atomic composition, doping level, and hole mobility in epitaxial diamond layers when doped with boron are reported. The layers are produced by chemical-vapor deposition. The possibilities of uniform doping with boron to a level in the range 5 × 10¹⁷ to ~10²⁰ at cm^–3 and of δ doping to the surface concentration (0.3–5) × 10¹³ at cm^–3 are shown. The conditions for precision ion etching of the structures are determined, and barrier and ohmic contacts to the layers are formed.     

Homoepitaxial single crystal diamond growth at different gas pressures and MPACVD reactor configurations

Homoepitaxial growth of single crystal diamond by microwave plasma chemical vapor deposition in a 2.45 GHz reactor was investigated at high microwave power density varied from 80 W/cm³ to 200 W/cm³. Two methods of achieving high microwave power densities were used (1) working at relatively high gas pressures without local increase of electric field and (2) using local increase of electric field by changing the reactor geometry (substrate holder configuration) at moderate gas pressures. The CVD diamond layers with thickness of 100–300µm were deposited in H₂–CH₄ gas mixture varying methane concentration, gas pressure and substrate temperature. The (100) HPHT single crystal diamond seeds 2.5 × 2.5 × 0.3 mm (type Ib) were used as substrates. The high microwave power density conditions allowed the achievement of the growth rate of high quality single crystal diamond up to 20 µm/h. Differences in single crystal diamond growth at the same microwave power density 200 W/cm³ for two process conditions—gas pressure 210 Torr (flat holder) and 145 Torr (trapezoid holder)—were studied. For understanding of growth process measurements of the gas temperature and the concentration of atomic hydrogen in plasma were made.