Microwave-assisted hydrothermally grown epitaxial ZnO films on 〈1 1 1〉 MgAl2O4 substrate

In this report, epitaxial ZnO films were grown on 〈1 1 1〉 MgAl2O4 single crystal substrates using Microwave Assisted Hydrothermal (MAH) method with microwave radiation heating (2.45 GHz) at 90 °C in a short time (within 15 min). Scanning electron microscopy confirms that these films possess smooth surface morphology with fully coalesced grains. In addition, photoluminescence (PL) measurements exhibit strong ultraviolet emission at room temperature, indicating potential applications for short-wave light-emitting photonic devices. The PL properties were improved by a thermal annealing process without generating structural defects. Hall measurements after thermal treatment show the carrier concentration to be of the order of 1019 cm−3 which is comparable to those grown by conventional solution methods. The MAH method will offer a rapid route to synthesize epitaxial ZnO films with good optical and electrical properties for various applications. - Graphical abstract: FESEM images showing the morphology and cross sectional view of ZnO films grown using microwave assisted hydrothermal method at 90 °C for 30 min. Highlights: ► Microwave Assisted Hydrothermal (MAH) method was introduced to synthesize epitaxial ZnO films. ► The films possess smooth surface morphology, fully coalesced grains with high optical properties. ► It exhibit good electrical properties (carrier concentration 1019 cm−3, mobility 19 cm2/Vs).