Optical and Structural Characteristics of Glancing Angle Deposition Synthesized Er₂O₃ Nanowires

The Er₂O₃ nanowires (NWs) were synthesized on Si substrate by using glancing angle deposition technique inside E-beam evaporator. The field-emission gun scanning electron microscopy (FEG-SEM) images showed perpendicular and highly porous Er₂O₃ NWs with average diameter ∼50 nm and length ∼350 nm. The crystallinity of the Er₂O₃ NWs improved with annealing but degraded at higher temperature annealing at 900 °C. Transmission electron microscopy (TEM) images show the unsymmetrical NW growth and grain size enhancement with increasing annealing temperature. In addition, two-fold enhanced absorption was observed for as deposited as compared to the annealed samples. A low intense photoluminescence was obtained for the as deposited sample as compared to the annealed samples due to the presence of defects and dangling bonds. The as deposited Er₂O₃ NW also showed a hydrophobic surface property with a contact angle of as high as 107.4° due to the air trapped in between Er₂O₃ NWs and oxygen vacancies which turned to hydrophilic surface with contact angle 27° and 25° when annealed at higher temperature of 750 °C and 900 °C respectively.