PHYSICAL PROPERTIES OF TYPE IIa AND Ib DIAMOND SINGLE CRYSTALS OBTAINED BY THE T-GRADIENT METHOD AT HRHT CONDITIONS

Abstract

The structural impurity state of diamond single crystals of type IIa and Ib obtained by the T-gradient method in NRNT conditions was studied by optical methods, and their thermal conductivity and electrical resistance were determined. A significant transmission in the ultraviolet (UV) region of the spectrum with a transmission edge of 221 nm was found for the type IIa sample, which indicates a high degree of structural perfection of the crystal. The type Ib sample is opaque in the UV region, low transmission is registered in the region from 290 nm with a sharp transmission edge near 450 nm. In the wavelength range of 800–1100 nm, both samples show transmission at the level of ~ 73%. By measuring the thermal conductivity of the samples, it was determined that the sample of diamond single crystal type IIa has a thermal conductivity of 1804 ± 36 W/(m×K), and the sample of diamond single crystal type Ib - respectively 948 ± 47 W/(m×K). The electrical resistance of the type IIa diamond plate is rs = 1.3×1011 Ohm×cm, and for the type Ib plate (yellow) it was outside the measurement range (rs> 1012 Ohm×cm).