Cathodoluminescence of HPHT type IIA diamond with boron concentration up to 0.03 ppm

A study was carried out of a single-crystal multi-sector plate of type IIb HPHT diamond with a minimum boron level detectable by IR absorption spectra. In the growth sectors $\{111\}$ and $\{110\}$, the boron concentration was 0.03 and 0.01 ppm. In the growth sectors $\{100\}$, $\{113\}$, $\{115\}$, the boron concentration is lower than the detection limit by absorption spectra. In the cathodoluminescence spectra of all sectors at a temperature of 77 K, broad structureless bands with maxima at 2.3 and 3.3 eV were revealed. The band with a maximum at 2.3 eV has two components with decay times in the ranges of 5–14 $\mu$s and 0.2–2 $\mu$s, respectively, differing in different growth sectors. The decay time of the band with a maximum of 3.3 eV is less than 100 ns. A difference in the intensity of luminescence of the sectors upon excitation by light of 220 nm and cathodoluminescence was revealed. The intensity of photoluminescence is minimal in the $\{110\}$ and $\{115\}$ sectors, and the cathodoluminescence of the $\{110\}$ sector is the most intense. Comparison with previous studies showed that with a decrease in the boron concentration in HPHT diamond, the intensity and decay time of CL decrease.