Enlarged broad band photodetection using Indium doped TiO sub(2) alloy thin film

• Published in: Journal of alloys and compounds Vol. 615; pp. 440 - 445
• Main Authors: Sarkar, Mitra Barun, Mondal, Aniruddha, Choudhuri, Bijit, Mahajan, Bikram Kishore, Chakrabartty, Shubhro, Ngangbam, Chitralekha
• Format: Journal Article
• Language: English
• Published: 05-12-2014
• Subjects: Devices; Diffusion; Expansion; Indium; Rutile; Secondary ion mass spectrometry; Thin films; Titanium dioxide
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2014.06.184

An instantaneous source of Indium (In) was used to dope the TiO sub(2) thin film (TF) on the Si substrate. The X-ray diffraction depicted the presence of rutile phases of TiO sub(2), which shifted to the lower value 61.7 from 61.9 (2[theta]). Secondary ion mass spectrometry (SIMS) reveals that the diffusion of Indium ion yield decreases sharply from the surface, as approached toward the TiO sub(2) TF-Si substrate interface. The bulk diffusion of In into TiO sub(2) was observed at a depth of 125-200 nm, up to the edge of TiO sub(2) TF. An inhomogeneous layer of In sub(x)Ti sub(y)O sub(2) alloy was formed during annealing process. An average of two fold enhanced photo absorption was recorded for the In doped TiO sub(2) TF in the 300-350 nm and 450-800 nm regions respectively. The main band gap of In doped TiO sub(2) was increased to 3.4 eV, whereas the large absorption edge was observed at 3.1 eV. The leakage current (34 nA at -0.5 V) of In doped TiO sub(2) TF detector was significantly reduced. A maximum 2.5 times (-3.5 V) enlarged photodetection has been observed for In doped TiO sub(2) TF device under white light illumination. The In doped TiO sub(2) TF detector shows the broad band photodetection, with an infinitesimal delay in its photo response time as compared to undoped TiO sub(2) TF.