Cubic ZnO films obtained at low pressure by molecular beam epitaxy

Abstract

A zinc oxide thin film in cubic crystalline phase, which is usually prepared under high pressure, has been grown on the MgO (001) substrate by a three-step growth using plasma-assisted molecular beam epitaxy. The cubic structure is confirmed by in-situ reflection high energy electron diffraction measurements and simulations. The x-ray photoelectron spectroscopy reveals that the outer-layer surface of the film (less than 5 nm thick) is of ZnO phase while the buffer layer above the substrate is of ZnMgO phase, which is further confirmed by the band edge transmissions at the wavelengths of about 390 nm and 280 nm, respectively. The x-ray diffraction exhibits no peaks related to wurtzite ZnO phase in the film. The cubic ZnO film is presumably considered to be of the rock-salt phase. This work suggests that the metastable cubic ZnO films, which are of applicational interest for p-type doping, can be epitaxially grown on the rock-salt substrates without the usually needed high pressure conditions.

Luminescent Properties of (004) Highly Oriented Cubic Zinc Blende ZnO Thin Films

“…Rosales-Córdova et al [10] reported the detection of the zinc blende phase in doped wurtzite ZnO thin films. Wang Xiao-Dan et al [11] reported on cubic ZnO thin films deposited at a low pressure by means of the molecular beam epitaxy technique. In a previous work [12], we reported the synthesis of metastable zinc blende ZnO thin films.…”

Electronic and thermal properties of Ag-doped single crystal zinc oxide via laser-induced technique

“…These two features can be utilized to design multi-segment thermal rectifiers, as demonstrated in our recent simulations. [46] By applying pressure [47] including strain engineering [48][49][50][51][52] or applying "chemical pressure" with chemical impurities [53] or alloying, [54] it is possible to tune properties of functional materials in different ways. Laser-induced method provides an alternative approach for doping with the advantage of flexibility by post-treatment and enables selected-area doping.…”

Mining and Restoration Monitoring of Rare Earth Element (REE) Exploitation by New Remote Sensing Indicators in Southern Jiangxi, China

“…It is clear that with their sensitivity and wide dynamic ranges, the integrated MRAIs can help distinguish the subtle differences between premining and mining and between mined and postmining management, of which the latter was actually graded into two levels for facilitating visualization in maps, though it may be divided into many more levels. Actually, Li et al (2018) and used NDVI to identify the REE mines locally [6,48], and Peng et al (2016) employed ecological quality index to analyze these areas in southern Jiangxi [47]. Largely speaking, their studies were relevant but had less sensitivity and accuracy than our approach, because some of them even failed to distinguish clouds from mines or required more indicators to compose the quality index.…”

“…It is worthwhile to mention that several authors have employed remote sensing to assess the rehabilitation or revegetation states of the mined areas [43] and have applied unmanned aerial vehicles (UAVs) for this purpose [44][45][46]. It is good to see that a limited number of studies were devoted to monitoring of REE mines [6,47,48]; however, none of them focused specifically on a comprehensive assessment of spatiotemporal characteristics of land degradation and restoration of the mining areas in southern Jiangxi. For this reason, the main objective of our study was to conduct monitoring and assessment research to fill this gap and to provide relevant advice for local governments for restoration management.…”