Growth of non-polar ZnO films on a-GaN/r-Al2O3 templates by radio-frequency magnetron sputtering

Co–Ga codoping effect on preferred growth orientations and properties of ferromagnetic ZnO thin films

“…The polarization effects can be minimized by growing wurtzite materials on non-polar [4] or semi-polar planes [5]. In the reported literature, most of the studies on non-polar/semi-polar ZnO-based films have been performed on single crystal substrates such as ZnO [6,7], Al 2 O 3 [8][9][10][11] and LaAlO 3 [12], where substrate-guided epitaxial growth is dominant. However, it is highly desirable to develop a more convenient and economical way to produce non-polar/semi-polar ZnO-based films through the fabrication of self-textured film on inexpensive amorphous surfaces.…”

A-axis oriented Zn0.72Mg0.28O epitaxial thin films with large second-order nonlinear susceptibility

“…Triple-axis x-ray diffraction measurements conclude that the Mg incorporation should increase the χ (2) under optical frequency electric field by strengthening electronic polarization rather than increasing the residual strain in the film. Furthermore, the annealed Zn 0.72 Mg 0.28 O exhibits an increase of 48% in laser-induced surface-damage threshold relative to [11][12][13][14][15][16][17][18][19][20] ZnO crystals. These findings open the way of the Zn 0.72 Mg 0.28 O thin films to ultrafast nonlinear optical devices.…”

Non-polar a -plane ZnO films grown on r -Al 2 O 3 substrates using GaN buffer layers

“…Therefore, it is important to seek solutions to mitigate the large lattice mismatch between ZnO and sapphire substrate to grow high-quality a-plane ZnO epilayers. Considering that GaN has a small lattice mismatch with ZnO (0.4% for the c-axis and 1.9% for the a-axis) and similar thermal expansion coefficients [7], it is considered as one of the best buffer layers [8][9][10]. However, GaN buffer layers and ZnO epilayers are grown by different techniques.…”