Nonequilibrium carrier dynamics in bulk HPHT diamond at two‐photon carrier generation

We demonstrate applicability of time‐resolved free‐carrier absorption and transient grating techniques for investigation of carrier recombination and diffusion features in a bulk diamond. Carrier injection into a 1 mm thick, IIa type high‐pressure high‐temperature grown layer was realized by two‐photon absorption of ∼5 ps laser pulse at 351 nm wavelength. Kinetics of differential transmission in 80–800 K range at various excess carrier densities provided carrier lifetimes of 360 ns at room temperature and their temperature dependences. A linear increase of carrier recombination rate with injection in 450–800 K range resulted in carrier lifetimes up to 1 ns and was fitted by effective coefficient B* = 2 × 10−11– 4 × 10−9 cm3/s. The latter process was attributed to a trap‐assisted Auger recombination (TAAR) with coefficient CTAAR = B*/NTrap and tentatively ascribed to nitrogen related traps. An ambipolar carrier mobility with its peak value of ∼1500 cm2/Vs at room temperature was measured by transient grating technique at ∼1.5 × 1015 cm−3 excess carrier density.