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

Abstract

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.

Optical study of carrier diffusion and recombination in CVD diamond

“…3 Results and discussion The interband excitation in diamond leads to production of a thin layer of excited carriers near the sample surface (penetration depth d $ 3-10 mm depending on excitation photon energy [10]) which is comparable or smaller than the diffusion length L ¼ ffiffiffiffiffiffiffiffiffiffi t FE D p ¼ 30 mm estimated from known values of diffusion constant and carrier lifetime [5,9]. The carrier dynamics is then influenced by diffusion and fast surface recombination [9].…”

Features of free carrier and exciton recombination, diffusion, and photoluminescence in undoped and phosphorus-doped diamond layers

“…Here  eh =  e + h is the free carrier absorption (FCA) cross section, consisting of electron, e , and hole,  h , absorption cross sections [11,17] (for probing excitons well below the diamond bandgap (at 1.17 eV) this relationship must also be valid [18]); T 0 and T(t) are the sample transmissions for probe wavelength without excitation and under excitation, respectively. In case when electrons and holes recombine independently (e.g.…”

Crystallite size dependent carrier recombination rate and thermal diffusivity in undoped and boron doped CVD diamond layers

“…In this way, excitation of the entire bulk crystal was achieved [6]. In the undoped microcrystalline (U-CVD) sample, the fast (80 ps) and slow (3-8 ns) recombination transients were observed and attributed to bulk intra-grain defects.…”

“…was generated by interband transitions [6]. Here DN 0 ¼ a 5 I 0 /hn 5 is the carrier density near surface (z ¼ 0), where hn 5 ¼ 5.82 eV is the quantum energy of 213 nm wavelength, I 0 is the excitation fluence.…”

“…À18 cm 2 is the total free carrier absorption (FCA) cross section [6], composed of electron (s e ) and hole (s h ) absorption cross sections. To elucidate impact of surface traps, differential reflectivity (DR) measurements were performed [15].…”