Point Defects in Two-Dimensional Indium Selenide as Tunable Single-Photon Sources

Abstract

In the past few years remarkable interest has been kindled by the development of nonclassical light sources and, in particular, of single-photon emitters (SPE), which represent fundamental building blocks for optical quantum technology. In this Letter, we analyze the stability and electronic properties of an InSe monolayer with point defects with the aim of demonstrating its applicability as an SPE. The presence of deep defect states within the InSe band gap is verified when considering substitutional defects with atoms belonging to group IV, V, and VI. In particular, the optical properties of Ge as substitution impurity of Se predicted by solving the Bethe−Salpeter equation on top of the GW corrected electronic states show that transitions between the valence band maximum and the defect state are responsible for the absorption and spontaneous emission processes, so that the latter results in a strongly peaked spectrum in the near-infrared. These properties, together with a high localization of the involved electronic states, appear encouraging in the quest for novel SPE materials.

Tailoring the Emission Wavelength of Color Centers in Hexagonal Boron Nitride for Quantum Applications

“…Many well-known single photon emitting systems have been investigated, including semiconductor quantum dots [ 11 , 12 ], color centers in solid-state crystals such as diamond [ 13 ], silicon carbide [ 14 ] or indium selenide [ 15 ], as well as trapped ions [ 16 ]. While single photons emitted from quantum dots have near-ideal photon purity and indistinguishability [ 17 ], they require low temperatures for operation.…”

Stability and Bandgap Engineering of In1−xGaxSe Monolayer

“…The Brillouin Zone of the primitive cell was sampled by employing a 6x6x1 Monkhorst-Pack grid [39] for monolayer unit cells and reduced accordingly as the supercell dimensions increased to ensure the same k-point density. All calculations were performed without considering the effect of spin-orbit coupling (SOC), since its inclusion does not strongly affect InSe and GaSe band structures [22,40,41].…”

“…Substitutional defects in a pristine monolayer may lead to a change in the lattice structure of the host material, resulting in a wide range bandgap tunability [20,21]. In our recent work [22], we defected 2D InSe with different substitutional impurities to generate well-defined and sharp defect states within the bandgap of the material, and we showed the possibility of using these new energy levels to achieve efficient emissions of single photons [23,24]. Here, considering the excellent optoelectronic properties and potential photonic applications shared by InSe and GaSe [25][26][27], and taking into account that they are almost lattice-matched and possess thickness-dependent tunable bandgaps [28,29] and very similar band structures (Figure 1b), we report a study of InGaSe compounds.…”

Strong Influence of the Anion Radius on the Passivation of Selenium Vacancy in Monolayer InSe: Insights from Time-Domain Ab Initio Analysis

“…20 Salomone et al have systematically studied the influence of passivation of different elements on the electronic structure of InSe and found that only group VI species can eliminate the trap states within the band gap. 21 Similarly, Castro Neto and co-authors have shown that oxygen doping can passivate the V Se . 19 V Se .…”

“…For example, Wang et al have demonstrated that group V species do not passivate the defect states created by V Se , while group VII species can repair the hole trap states of V Se . Salomone et al have systematically studied the influence of passivation of different elements on the electronic structure of InSe and found that only group VI species can eliminate the trap states within the band gap . Similarly, Castro Neto and co-authors have shown that oxygen doping can passivate the V Se .…”