Shinichi Shikata

Dislocation Analysis of p Type and Insulating HPHT Diamond Seed Crystals

The dislocation of a p+ high-temperature, high-pressure (HPHT) seed crystal is analyzed by X-ray topography using a SR light source, and compared with that of an insulating HPHT seed crystal. The dislocation density of the typical insulating HPHT substrate is around 250 cm-2. Over several years, significant progress has been achieved in reducing the dislocation density of the typical insulating HPHT substrate from the order of 104–105 cm-2 to 102 cm-2. The p+ HPHT seed crystal has unique properties, especially in terms of the number of stacking faults (SFs), and very clear growth sector boundaries with dislocation densities of up to 3000 cm-2. As most research activities have been focused on the “insulating substrate” in HPHT growth technology for a long time, several challenges need to be overcome with respect to the growth of a p+ HPHT crystal.

Influence of Dislocations to the Diamond SBD Reverse Characteristics

Several studies have been carried out regarding the influence of dislocations on device characteristics; however, most of them had been limited to pseudo-vertical structures using high pressure high temperature (HPHT) insulating material as the substrate. In this study, we have investigated the influence of dislocations to the devices using vertical structure SBD on p+ HPHT substrate. SBDs were selectively fabricated on specific dislocation areas. The SBD fabricated on the threading dislocation area indicated fatal influence of the dislocation on the device characteristics.

Formation of Nitrogen-Vacancy Centers in Homoepitaxial Diamond Thin Films Grown via Microwave Plasma-Assisted Chemical Vapor Deposition

A model for controlling the two-dimensional distribution of negatively charged nitrogen-vacancy (NV- ) fluorescent centers near the surface of a diamond crystal is presented, using only a microwave plasma-assisted chemical vapor deposition (CVD) method. In this approach, a CVD diamond layer is homoepitaxialy grown via microwave plasma-assisted CVD using an isotopically enriched methane (12CH4), hydrogen (H2), and nitrogen (N2) gas mixture on patterned diamond (0 0 1). When the surface is imaged by means of confocal microscope photoluminescence mapping, fine grooves are observed to have been generated artificially on the diamond surface. NV- centers are found to be distributed selectively into these grooves. These results demonstrate an effective means for the formation of NV- centers of selectable size and density via microwave plasma-assisted CVD, with potential application in the production of diamond quantum sensors.