X-Ray Topographic Study of a Homoepitaxial Diamond Layer on an Ultraviolet-Irradiated Precision Polished Substrate

Abstract

Suitable techniques for the growth of high-quality single-crystal diamond are needed in order to use single--crystal diamond in power devices. Because the ion plantation technique cannot be used for diamond doping, a drift layer and a conduction layer for a diamond power device were grown by chemical vapor deposition. An important challenge in this eld is to reduce the dislocation density in the epitaxial layer. The dislocation density was found to increase during the chemical vapor deposition process. Because a defective surface is one cause of increased dislocation density, the use of a UV-polished substrate having no scratches due to mechanical polishing was investigated.

Atomically flat diamond (100) surface formation by anisotropic etching of solid-solution reaction of carbon into nickel

“…In Fig. 3(b), the pit density ranges from 10 7 to 10 9 cm −2 , which is substantially greater than the typical dislocation pit density of HPHT diamond, i.e., approximately 10 5 cm −2 [32,33]. Therefore, the pits in Fig.…”

Imaging of diamond defect sites by electron-beam-induced current

“…It has been noticed that defect density (~10 3 /cm 2 ) of type IIa HPHT diamond [2,9] is about two orders of magnitude smaller than that (~10 5 /cm 2 ) of type Ib HPHT diamonds [3,11,13]. The difference between IIa and Ib type HPHT diamonds is mostly the concentration of nitrogen impurity induced during HPHT growth process.…”

“…Typical defect densities as found by X-ray topography vary. They range from~400/cm 2 [2] for (111) face and~2000/cm 2 [9] for (100) surface of a IIa type HPHT diamond to~10 4 /cm 2 for (100) face of a CVD and Ib type HPHT diamond [13].…”

Polishing, preparation and patterning of diamond for device applications

“…A small number of studies have used X-ray topography to specifically examine the effect of polishing on the quality of epitaxially-grown diamond. [6,19] Friel et al compared different polishes, known to have induced different levels of damage and observed a clear improvement in the crystalline quality of the diamond grown on less damaged and plasma surface treated substrates ( Figure 14. [6] However, the observations are solely qualitative.…”

“…UV photochemically enhanced polishing ( Figure 6) has also been investigated by Watanabe et al, achieving sub-nanometer roughness and reduced defect density. [18,19] These techniques, although encouraging for the future of diamond polishing, are still at an early development stage, yet to be applied to single crystal diamond and, importantly, lacking in the subsequent characterisation of the sub-surface effects of the process.…”