Structural and optical properties of glancing angle deposited In2O3 columnar arrays and Si/In2O3 photodetector

Ordered and perpendicular columnar arrays of In₂O₃ were synthesized on conducting ITO electrode by a simple glancing angle deposition (GLAD) technique. The as-deposited In₂O₃ columns were investigated by field emission gun-scanning electron microscope (FEG-SEM). The average length and diameter of the columns were estimated ～400 nm and ～100 nm, respectively. The morphology of the structure was examined by transmission electron microscopy (TEM). X-ray diffraction (XRD) analysis shows the polycrystalline nature of the sample which was verified by selective area electron diffraction (SAED) analysis. The growth mechanism and optical properties of the columns were also discussed. Optical absorption shows that In₂O₃ columns have a high band to band transition at ～3.75 eV. The ultraviolet and green emissions were obtained from the In₂O₃ columnar arrays. The P-N junction was formed between In₂O₃ and P-type Si substrate. The GLAD synthesized In₂O₃ film exhibits low current conduction compared to In₂O₃ TF. However, the Si/GLAD-In₂O₃ detector shows ～1.5 times enhanced photoresponsivity than that of Si/In₂O₃ TF.