Carrier recombination and diffusion in high-purity diamond after electron irradiation and annealing
Paulius Grivickas, Patrik Ščajev, N.M. Kazuchits, С. Б. Ластовский, Lars F. Voss, Adam Conway, A.V. Mazanik, O.V. Korolik, V. Bikbajevas, V. Grivickas
Abstract
Carrier-transport mechanisms are studied in high-purity diamond irradiated with 6 MeV electrons in the dose range of 1012–1016 cm−2 and annealed at different temperatures up to 1450 °C. Lifetimes and diffusion coefficients are extracted using two pump–probe techniques based on free-carrier absorption and transient-grating principles and then correlated with the corresponding defect evolution from spectroscopic measurements. The neutral monovacancy is revealed as the main carrier recombination center in the as-irradiated diamond, providing bipolar carrier lifetimes of a few nanoseconds at the highest irradiation dose. Carrier-capture cross sections are reduced during annealing as vacancies aggregate into divacancies at ≤1000 °C and extended vacancy clusters at 1450 °C.