Investigation of Line Width Narrowing and Spectral Jumps of Single Stable Defect Centers in ZnO at Cryogenic Temperature

Abstract

Finding new solid state defect centers in novel host materials is crucial for realizing integrated hybrid quantum photonic devices. We present a preparation method for defect centers with photostable bright single photon emission in zinc oxide, a material with promising properties in terms of processability, availability, and applications. A detailed optical study reveals a complex dynamic of intensity fluctuations at room temperature. Measurements at cryogenic temperatures show very sharp (<60 GHz) zero phonon lines (ZPLs) at 580 nm to 620 nm (≈ 2.0 eV) with frozen out fast fluctuations. Remaining discrete jumps of the ZPL, which depend on the excitation power, are observed. The low temperature results will narrow down speculations on the origin of visible-near-infrared (NIR) wavelength defect emission in zinc oxide and provide a basis for improved theoretical models.

Room-temperature single-photon emission from zinc oxide nanoparticle defects and their in vitro photostable intrinsic fluorescence

“…The abrupt leading edge was due to a 570 nm long-pass filter. The emission range matches the previous reports by Morfa et al [22], Choi et al [23,24], and Neitzke et al [26], where their single defects also showed broad red fluorescence. In this study, the results reveal that ZnO optical defects have distinct and resolvable emission peaks compared to the aforementioned work at room temperature.…”

“…In this study, the results reveal that ZnO optical defects have distinct and resolvable emission peaks compared to the aforementioned work at room temperature. It must be noted that Neitzke et al [26] also observed a very narrow zero phonon line at 580 nm when they measured their ZnO optical defects at cryogenic temperatures, which greatly suppresses their phonon sideband emission from 600 to 750 nm.…”

“…Very few systems demonstrate room-temperature single-photon emission and these include diamond [19], silicon carbide defects [20], and CdSe/ZnS quantum dots [21]. More recently, ZnO has been added to this list where its structure has been observed to host defect-related single emitters at room temperature [22][23][24][25][26].…”

Zinc Oxide Nanophotonics

“…Other groups found the singlephoton emission ranging from around 1.55 to 2.21 eV. Jungwirth et al measured 19 different defects in ZnO [10] and about 30 defect center locations have been investigated by Neitzke et al [51]. They obtained antibunching curves with similar spectral range.…”

“…For clear understanding of the ZnO defects, low temperature PL measurement was performed by Neitzke et al [51]. Sixteen defects from the same ZnO sample were investigated at 5 K and Figure 4 shows one of the PL spectra of the defects consisting of the shape of ZPL and a phonon sideband.…”