GaN as a Material Platform for Single‐Photon Emitters: Insights from Ab Initio Study

Abstract

GaN with atom defects is a rising material platform for single‐photon emitter (SPE) recently due to their room‐temperature working conditions, high emission rate, narrow emission line‐width and mature processing technology. However, the SPE mechanism still remains unclear to date, which greatly hinders the progress of GaN based SPE. Herein, systematic ab initio calculations predict and identify two kinds of intrinsic point defects NGa and NGaVN in GaN, which can be response for the widely observed SPEs. The formation energy, band structure, transition mechanism, and orbital composition are systematically investigated. The results indicate that NGaVN° possesses a large zero‐phonon line (ZPL) of 1.98 eV and a short lifetime of 3.56 ns, which may be one of the most possible origins of SPEs in visible wavelengths. The calculation results coincide well with our measured ZPL (1.92 eV) and lifetime (1.14 ns), as well as the experimental results reported previously. This work also predicts that NGa0 and NGaVN+1 can produce SPEs at fiber telecommunications band (0.84 and 0.94 eV, respectively). These results give deep insights into the SPE emission mechanism in GaN and bridge the gap between the realized SPEs and the underlying physical mechanism.

Optical Dipole Structure and Orientation of GaN Defect Single-Photon Emitters

“…SIMS also showed carbon, hydrogen, and oxygen concentrations of ∼5 × 10 16 /cm 3 , ∼3 × 10 17 /cm 3 , and ∼10 16 /cm 3 , respectively. Whereas the defects mentioned above are all extrinsic, recently an intrinsic antisite-vacancy complex N Ga V N (also of the type X Ga Y N ) has also been suggested as a possible candidate for SPEs with emission wavelengths close to 625 nm . As a final word, we note here that the SPE density in our samples is less than 10 10 /cm 3 .…”

“…Whereas the defects mentioned above are all extrinsic, recently an intrinsic antisitevacancy complex N Ga V N (also of the type X Ga Y N ) has also been suggested as a possible candidate for SPEs with emission wavelengths close to 625 nm. 24 As a final word, we note here that the SPE density in our samples is less than 10 10 /cm 3 . This means that impurity atoms in concentrations much lower than the SIMS detection limit could also underlie the observed SPEs in our samples.…”

“…If one assumes that the optical dipole moment is along the axis of the X – Y complex, then this family of defects could explain the measured dipole orientations (angles θ o and φ o ) of the SPEs (note the 109.5 and 90° angles between the c -axis and the nearest Ga–N bonds and the nearest Ga–Ga (or N–N) directions, respectively, in Figure b). Several first-principles studies have been reported for point defects in GaN. − Point defects in which one of X and Y is carbon or iron and the other is carbon, hydrogen, oxygen, or a vacancy are promising candidates as computations have shown these point defects to have relatively small formation energies and their computed ZPL photon emission energies are in the neighborhood of the observed emission energies. − However, computed optical dipole orientations have not been reported in the literature for all of these defects. In the case when both X and Y are carbon atoms, the optical dipoles are known to be oriented along the X – Y axis .…”

Sn‐Doped Cs3Cu2I5 Microcrystals with High Photoluminescence and Hydrochromic Stability for Anti‐Counterfeiting and Encryption Applications

“…To achieve computational savings, DFT calculations in PWMAT with graphics processing unit (GPU) acceleration are used. [39,40] Various doping ratios are used in the computational model to investigate its impact on the overall structure because the experimentally optimal doping quantity is found to be 0.3%. However, the calculations do not support such a huge amount of computation structural doping model.…”

The Quenching Mechanism and Suppressing Method of Single-Photon Emitters from Point Defects in GaN

“…GaN has been considered as one of the most promising semiconductors for SPEs due to its mature commercial processing technology, and the extremely wide band gap, which could suppress the interaction between the two-level system and the host states, weaken the photoacoustic coupling, and result in a narrow zero-phonon line (ZPL). Since 2017, room temperature SPEs based on GaN with excellent performance have been successfully verified in both experiment and theory, ,, and research toward practical applications is in full swing.…”