MBE Growth and Optical Properties of Isotopically Purified ZnSe Heterostructures

Abstract

Wide-gap II/VI heterostructures (HS) and quantum wells (QW) composed of ZnSe, CdSe, MgSe, and their ternary and quaternary compounds are attractive candidates for modern quantum optical devices such as single photon sources and optically controlled spin qubits in the visible spectral range. In contrast to similar III/V semiconductor based devices, generally, most of the II/VI compounds allow for isotope purification toward zero-nuclearspin species in the semiconductor environment. Using the same molecular beam epitaxy (MBE) system for natural and isotopically purified materials opposes the challenge of achieving superior isotope purity, for example, of Zn and Se species on the background of operation of the other effusion cells filled with natural isotopes. Here we report on the crystallographic and optical properties of ZnMgSe/ZnSe heterostructures and quantum wells grown by using 64 Zn and 80 Se isotopes and Mg with natural isotope distribution. We present a detailed quantitative secondary ion mass spectrometry (SIMS) analysis, which confirms that an extremely high grade of isotope purification of the ZnSe can be maintained, although natural and enriched Zn and Se elements are used in the same MBE system. This pioneering growth study forms a solid base to generate a spin vacuum ZnSe host crystal that is particularly suited for future studies on the dynamics of localized spins in II/VI heterostructures on a strongly extended coherence time scale.

Single quantum emitters with spin ground states based on Cl bound excitons in ZnSe

“…Observation of two-electron-satellite and circular polarization under Faraday magnetic field indicates a single electron ground state which could be employed for spin-qubit applications. Isotopic purification of the host crystal to be nuclear spin free makes Cl impurities an attractive candidate for long-lived memory qubits [17] and providing a route towards optically bright spin qubits with long coherence times. These unique aspects could allow a wide range of applications in quantum information processing.…”

“…Ensemble measurements have also revealed the potential for optical active spin qubits [16]. Recently, the growth of isotopically purified (Zn,Mg)Se/ZnSe quantum well structures was also demonstrated [17]. Spin purification of the host crystal further resulted in extended spin coherence times [18].…”

Cavity-Enhanced Single-Photon Emission from a Single Impurity-Bound Exciton in ZnSe

“…12−17 These emitters also possess a natural spin ground state that can act as a qubit, opening the possibility to realize efficient spin-photon interfaces. 12,15,17,18 In addition, ZnSe quantum wells can be grown and isotopically purified 19 to deplete the nuclear spin background, which should lead to a drastic increase in the spin dephasing times. However, fully harnessing the potential of these emitters for quantum applications requires methods to extract their photon emissions with high efficiency.…”

Efficient Single-Photon Sources Based on Chlorine-Doped ZnSe Nanopillars with Growth Controlled Emission Energy

“…Zinc selenide (ZnSe) has been intensively investigated over the last few decades as a promising II–VI semiconductor material with a direct bandgap possessing excellent properties for optical and electronic applications. − In this regard, ZnSe has emerged as a promising host crystal matrix for impurity-bound-exciton-related emission of single photons. , In particular, the ability to generate indistinguishable single photons was recently demonstrated with fluorine (F) donors, spatially isolated in epitaxially grown ZnSe/ZnMgSe QW nanostructures (i.e., ZnSe:F) . It should be noted that no tuning was applied to match the emission wavelength of two independent ZnSe:F emitters in that case, which reflects a low device-to-device spectral variation for the impurity-based SPSs.…”