Study on Preparation and Photocurrent Response Properties of In/In2O3/TiO2 Nanotubes Arrays Compound Heterojunction Semiconductor

Abstract

TNTs were prepared in ethylene glycol with 0.5wt%NH4F and 1.5Vol%H2O by the anode potential of 60V. In/In2O3/TiO2 nanotube arrays (TNTs) heterojunction semiconductor was prepared by two electrochemical steps of reduction and oxidation in 0.01 mol/L InCl3 ethanol solution. The element In and In2O3 nanofibers were distributed in and on the TNTs by SEM figures. By the photocurrent results, TNTs photocurrent response was reinforced by In2O3 and In modification in UV and visible light region. The monochromatic incident photon-to-electron conversion efficiency (IPCE) reached to 58% under the 350nm light radiation and was nearly 5 times that of TNTs. Two oxidation phases were got from the photocurrent data (the energy band gap Eg = 3.08eV and Eg = 2.2 eV), which was propitious to the absorption light red shift and response under the visible light. The flat band potentials shifted to electric positive direction for In/TNTs prepared by one step of reduction or In/In2O3/TNTs prepared by two steps of reduction and oxidation according to the Mott-Schottky curve. The donor density (ND) of the In/In2O3/TNTs was slightly higher than TNTs and the ND of In/TNTs was the highest for 14.6 times that of TNTs. The results show that heterojunction is formed between In2O3 and TNTs to promote visible light absorption and carrier separation. A great deal of element In makes the photo generated electrons and holes recombination to reduce the photocurrent response, but a small amount of element In can reduce the Eg of semiconductor and promote the absorption light to red shift for TNTs. The transfer mechanism of In and In2O3 modified by TNTs was discussed.