Optical Characterization of Structural Quality in the Formation of In₂O₃ Thin-Film Nanostructures

We report on optical examination of structural properties of cubic-In 2 O 3 ( c -In 2 O 3 ) degenerate-semiconducting-oxide thin-film nanostructures grown on Si (100) substrates using vapor transport method driven with vapor–liquid–solid mechanism. Two different types of dense (A) and loose (B) c -In 2 O 3 thin-film nanorods have been, respectively, characterized by photoluminescence (PL), time-resolved photoluminescence (TRPL), thermoreflectance (TR), and Hall and resistivity measurements. Strong excitonic emissions detected from the PL results of the A and B samples identify the high-crystalline quality of the arrow-type c -In 2 O 3 nanorods. Theoretical modeling fits on the TRPL results of the A and B samples characterize and identify defect mechanisms of the nanostructured thin films. Near-band-edge and above-band-edge transitions such as excitons, direct band gap, and Burstein–Moss shift (above direct gap) in the degenerate A and B c -In 2 O 3 have also been detected by TR measurement. Field-emission scanning electron microscopy and field-emission transmission electron microscopy have been implemented to facilitate the observed optical measurement results of the c -In 2 O 3 . All experimental analyses show that the TR, PL, and TRPL measurements are powerful techniques for optical characterization of structure and optoelectronics properties of the c -In 2 O 3 degenerate nanostructured thin film available for transparent optoelectronics use.