Effects of argon/nitrogen sputtering gas on the microstructural, crystallographic and piezoelectric properties of AlN thin films

• Main Authors: Samad M.I.A., Noor M.M., Nayan N., Bakar A.S.A., Mansor M., Zuhdi A.W.M., Hamzah A.A., Latif R.
• Other Authors: 57768220600
• Format: Article
• Published: Acta Materialia Inc 2024
• Subjects: Aluminium nitride; Argon plasma; Crystallography; Piezoelectric force microscopy (PFM); Radio frequency (RF) sputtering; Argon; Crystal structure; Gas adsorption; III-V semiconductors; Nitrogen; Oxygen; Piezoelectricity; Single crystals; Sputtering; Temperature; Thin films; AlN thin films; Argon plasmas; Crystals structures; Micro-structural properties; Oxygen content; Piezoelectric force microscopy; Radio frequency sputtering; Sputtering gas; Thin film layers; Aluminum nitride

The growth of highly crystalline c-plane AlN �002� is extremely difficult, entailing high temperature and ultra-high vacuum condition. In sputtering technique, the addition of nitrogen into argon sputtering gas can significantly assist the formation of AlN �002� at low temperature. We incorporated purified nitrogen gas and observed the consistent formation of single crystal �002� AlN thin film layer sputter-deposited on Mo/Si substrate from the AlN ceramic target. Small presence of oxygen content within AlN crystal relates to the preferential growth of AlN �002�. High oxygen content in AlN thin film due to the use of unpurified nitrogen and argon only sputtering gas prefers the formation of AlN �100�. Different AlN crystal structure has shown distinct thin film properties and piezoelectric response. This work provides a method to control the crystal structure of the sputter-deposited AlN thin film layer, either c-plane AlN �002�, a-plane AlN �100� or polycrystalline AlN. � 2022 Acta Materialia Inc.