Growth of Bulky Single Crystalline Films of (Zn,Mg)O Alloy Semiconductors by Liquid Phase Epitaxy

Abstract

Very thick (about 0.5 mm) single crystalline films of (Zn1−x Mg x )O solid solution have been grown by a liquid phase epitaxy (LPE) technique. The source materials, ZnO and MgO, were dissolved in a molten PbO-Bi2O3 flux and deposited on ZnO substrates as epitaxial (Zn1−x Mg x )O layers. The (Zn1−x Mg x )O layers thus obtained showed high crystallinity, similar to that of the ZnO substrate, and exhibited n-type conductivity with relatively high Hall mobilities (>90 cm2 V−1 s−1 for x = 0.1 at room temperature). Moreover, the activation energy of the mobile electrons was about 50 meV, and this value was independent of the MgO fraction. Since LPE is an appropriate technique for growing large area films, we examined the growth of (Zn,Mg)O thick films on 2 in. diameter ZnO substrates. The Mg concentration in the LPE grown layer was quite uniform, and the Li concentration was two or three orders lower than an ordinary ZnO substrate.

Properties of gallium- and aluminum-doped bulk ZnO obtained from single-crystals grown by liquid phase epitaxy

“…The undoped samples showed relatively high n of the order of 10 17 cm -3 because of unintentional Al contamination in nominally undoped ZnO grown by LPE. As described in our previous reports [22,23], the undoped samples prepared using our homemade LPE furnaces were contaminated with Al that originated from furnace materials. In the nominally undoped samples, n was close to the concentration of Al contamination.…”

“…The procedure for LPE for growing ZnO on a ZnO substrate has been shown in our previous studies [22,23]. In this study, we used pure ZnO, Al 2 O 3 , and Ga 2 O 3 powders as source materials for LPE growth, and a PbO-Bi 2 O 3 flux was used.…”

“…In our research, we have succeeded in growing high-quality bulk crystals of (Zn, Mg)O alloys by liquid phase epitaxy (LPE) using a PbO-Bi 2 O 3 flux [22,23]. Based on our previous research, the flux method appears to have more flexibility than the hydrothermal method.…”

Selective Homoepitaxial Growth of ZnO Layers on c(+)-Surface by Solvothermal Reaction in Water–Ethylene Glycol Solvent

“…When the homoepitaxial growth can be applied to doped films, it could be a simple method for optical and magnetic devices. 12 , 14 …”

“…ZnO films have been fabricated by several techniques, such as sputtering, 7 chemical vapor deposition (CVD), 8 , 9 molecular beam epitaxy (MBE), 10 − 12 pulsed laser deposition, 13 and liquid phase epitaxy. 14 Solution-based methods are simple and environmentally friendly and can be used for the preparation of complex nanostructures at low temperatures. ZnO films and nanostructures have been synthesized using solution-based methods such as chemical bath deposition, 15 − 20 hydrothermal deposition, 21 electrodeposition, 22 spin-spraying, 23 and dip-coating.…”