Excitons and fundamental transport properties of diamond under photo‐injection

Abstract

Abstractauthoren Exciton diffusivity and carrier mobility are key features in determining transport properties of a material. The optimum values required for high‐performance devices are expected to be realized in undoped intrinsic materials. Diamond, one of the emergent high‐mobility materials, has a wide band gap suited for use in power electronics and optoelectronics. For many years, however, mobility measurement for diamond has been limited by carrier freezing at deep impurity levels. Recently, attempts at utilizing photoexcited carriers in undoped diamond have been made in a wide temperature range and various excitation schemes. A series of investigations demonstrated a wealth of intriguing observations such as dominant role of excitons and emergence of low‐temperature anomaly in momentum relaxation. This article highlights recent experimental advances and progresses in understanding transport properties of photoexcited intrinsic diamond.

Far‐UV‐Excited Luminescence of Nitrogen‐Vacancy Centers: Evidence for Diamonds in Space

“…[27] In amaterial like diamond with an indirect band gap,PLis known to occur at as ubstantial distance from the point of excitation. [28] Ther eason is that the interband excitation creates free electrons and holes in the crystal, forming excitons that can travel in ap article-like fashion through the lattice.The exciton diffusion length in type Ib diamond is approximately 1 mm, [29] much longer than the separation distance of approximately 10 nm between NV À centers in our samples.W ithin this distance,t he energy (ca. 5.47 eV) released from the electron-hole recombination suffices to ionize the negatively charged defects to form electronically excited neutral centers,which requires atotal energy of 0.7 + 1.945 + 2.156 % 4.8 eV (inset in Figure 4).…”

Far‐UV‐Excited Luminescence of Nitrogen‐Vacancy Centers: Evidence for Diamonds in Space

“…The reason is that the interband excitation creates free electrons and holes in the crystal, forming excitons that can travel in a particle‐like fashion through the lattice. The exciton diffusion length in type Ib diamond is approximately 1 μm, much longer than the separation distance of approximately 10 nm between NV − centers in our samples. Within this distance, the energy (ca.…”

Spin polarization of photoelectrons in GaAs excited by twisted photons

“…In many cases, excitonic contributions may be considerable even for vertical transitions in direct vicinity to the Γ-point . This is known not to be the case for GaAs photo-injection [31], so we assume no excitonic contribution in this work. The remote contributions are accounted for in expansion coefficients S(k k k), which depend on the global symmetries of the crystal lattice and can be extracted from the group theory analysis.…”