Low-Temperature Epitaxial Growth of AlN Thin Films on a Mo Electrode/Sapphire Substrate Using Reactive Sputtering

High-crystalline aluminum nitride (AlN) thin films are essential for device applications, and epitaxial growth is a promising approach to improve their crystalline quality. However, high substrate temperature usually required the growth, which not compatible with complementary metal-oxide-semiconductor (CMOS) process. Furthermore, it very difficult obtain AlN on deposited metal layers that sometimes necessary bottom electrodes. In this work, were successfully prepared molybdenum (Mo) electrode/sapphire using reactive sputtering at low temperature. The structural properties, including out-of-plane in-plane relationships between film substrate, investigated X-ray diffraction (XRD) 2?-?, rocking curve, pole figure scans. Additional analyses scanning electron microscopy (SEM), atomic force (AFM), transmission (TEM) also carried out. It was shown highly c-axis-oriented grown epitaxially Mo/sapphire an relationship of [112¯0]//sapphire [101¯0]. This attributed ordered oriented Mo electrode layer sapphire substrate. contrast, deposition Mo/SiO2/Si under same conditions caused poorly polycrystalline structure. There coexisted two different low-crystalline phases (110) (211) in SiO2/Si led mosaicity structure films.