Growth of Mg_xZn_(1-x)O/ZnO Heterostructures by Liquid Phase Epitaxy

摘要

We investigate the fabrication of thermodynamically stable (0001)Mg_xZn_(1-x)O/ZnO wurtzite heterostructures by liquid phase epitaxy (LPE) for the solid-solution range of 0 ≤ x ≤ 0.2. A continuous reaction of MgCl_2/ZnCl_2 and K_2CO_3 is applied to form Mg_xZn_(1-x)O. Mirror-like films of the thickness ≤ 4 μm have been grown uniformly on hydrothermal (0001)ZnO substrates for the first time by LPE. The solubility limit of 6 mol % Mg on Zn sites in ZnO at 640℃ is revealed. For the concentration range of 0 ≤ x ≤ 0.06 the lattice parameter c decreases from 5.207 to 5.203 A, the X-ray rocking curve ω-scan full-width half-maximum (FWHM) increases from 15 to 176 arcsec, and the donor-bound low-temperature (3 K) photoluminescence (PL) peak signal from the band gap shifts from 3.36 to 3.43 eV, respectively. The critical film thickness for misfit-induced cracking is estimated for Mg_xZn_(1-x)O films with x ≤ 0.3 grown on (0001) and (0001)ZnO.