Homoepitaxy of ZnO: from the substrates to doping

Abstract

We report on the homoepitaxial growth of ZnO thin films by chemical vapor deposition techniques. The preparation of the ZnO substrates after mechanical polishing employed a high temperature annealing step which produced atomically flat surfaces and removed all of the surface and subsurface damage. Two dimensional epitaxial growth was achieved without an additional buffer layer. The substrate had a rocking curve with a full width at half maximum of 27″ which can be compared with that of the film of 17″. The films had superior band edge luminescence as compared with the substrate for which the green luminescence band is dominating. The impurity content in the substrates especially Li is reduced by the high temperature annealing step and drops further close to the detection limit in the films. The low substrate temperatures around 660 °C allow for the incorporation of nitrogen on oxygen site as a shallow acceptor.

Homoepitaxial ZnO thin films by PLD: Structural properties

“…1 by comparing a film grown on as-received substrate with two other films deposited on annealed substrates. The FWHM of the rocking curves of the homoepitaxial PLD films is comparable to best values from LPE (32 arcsec [7]), or CVD (17 arcsec [10]). AFM images with atomic zresolution were taken with a VEECO Dimension 3100 with Nanoscope IV controller in tapping mode.…”

“…The O-face polarity of the homoepitaxial ZnO films is confirmed by convergent beam electron diffraction. Intensity fringes in triple axis ZnO(00.2) 2Θ−ω scan of the undoped homoepitaxial film E1331 with thickness 980 ± 30 nm, indicating smooth interface and surface 17 arcsec was measured for an undoped homoepitaxial film grown by chemical vapour deposition (CVD) [10].…”

Substrates Grown from the Vapor for ZnO Homoepitaxy

“…The literature data is widely ranging from 0.4 nm [10] to 20 nm [11]. These and other reports [12][13][14] demonstrate the dependence of the roughness on the way the substrate was prepared, the method of the film growth and the film thickness. Additionally, the quality of ALD layers was found in this work dependent on the crystallographic orientation of the samples.…”

“…5 doped with copper. It is the effect of the crystallographic orientation (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) of the sample [8,9]. On the sample No.…”

Exciton confinement in homo- and heteroepitaxial ZnO/Zn1 − xMgxO quantum wells with x < 0.1

“…However, only very few results of homoepitaxial growth of polar ZnO/(ZnMg)O SQWs have been reported, 20 although this growth technique can lead to improved structural, optical, and electrical properties of the resulting ZnO films. [21][22][23] In this paper, we compare the structural and optical properties of hetero-and homoepitaxially grown ZnO/Zn 1 À x Mg x O single quantum well structures and discuss the role of exciton localization and of internal electric fields in SQWs with low Mg content.…”