Improved photo-detection from annealed SiOx–In2−xO3−y axial heterostructure nanocolumns

Abstract

SiOx–In2−xO3−y heterostructure nano-columnar arrays are synthesized on n-type Si substrate by the glancing angle deposition technique. The transmission electron microscopy image shows the formation of heterostructures. A typical annealed SiOx–In2−xO3−y nanocolumn consists of ∼70 nm SiOx and ∼170 nm long In2−xO3−y, which is polycrystalline in nature. Two-fold improved photon absorption is observed for the annealed SiOx–In2−xO3−y compared with the as-deposited columnar arrays. The SiOx–In2−xO3−y annealed device exhibits a low leakage current of 2.8 × 10−7 A (−5 V). A ∼352 times enhanced photosensitivity is observed for the annealed device at −1.5 V as compared with the as-deposited one. The hole-trapping process at the metal–annealed nanocolumn interface states efficiently reduces the depletion width under reverse bias and the Schottky height at the junction, which produces enhanced electron tunnelling and, therefore, enhanced device photosensitivity.