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.