Hybrid Fabrication of Highly Rectifying <inline-formula> <tex-math notation="LaTeX">$p$ </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">$n$ </tex-math></inline-formula> Homojunction Based on Nanostructured TiO₂

Abstract

Present report concerns fabrication of nanostructured TiO 2 -based p-n homojunction, by the hybrid technique involving deposition of sol-gel grown not intentionally doped p-type TiO 2 nanoparticle layer over the electrochemically grown aligned, n-type TiO 2 nanotube array. The Au/ p-TiO 2 / n-TiO 2 nanotube/Ti device was found to offer the ideality factor and the cut-in voltage of ∼4 and ∼1.2 V, respectively, in the temperature range of 30°C-80°C. The structural advantages of TiO 2 nanotubes, owing to the large junction area, eventually offered attractive rectifying behavior (∼10 3 orders) of the fabricated junction.Index Terms-Sol-gel p-TiO 2 , electrochemical n-TiO 2 nanotubes, p-n homojunction, high rectification, low ideality factor.

A highly stable room temperature titania nanostructure-based thin film transistor (TFT) alcohol sensor

“…In the present study, 100 ppm is found to be the optimum alcohol concentrations for TiO 2 surfaces beyond that increase in adsorption scattering and lower gas sticking coefficient (θ) makes surface saturation leading to the constant drain current. Carrier trapping found to be dominant in air ambient with higher sweep rates [3,[46][47]. On the other hand, detrapping of the same happens through charge transfer from surface to the sensing channel.…”

“…3 Carrier trapping is dominant in ambient air with higher sweep rates. 3,46,47 On the other hand, the detrapping of the same occurs through charge transfer from the surface to the sensing channel. Such a charge transfer process (due to surface interaction with target gases) causes strong accumulation at the sensing channel.…”

“…48 The gate capacitance (C OX ) decreases with the increase in surface reaction or carrier detrapping phenomena and for the same reason, the interface state capacitance increases. 47,48 The interface capacitance C int = (dQ int )/(dΨ S ) = q(dn int )/(dE S ) F/cm 2 (E S = energy at SiO 2 -TiO 2 interface, Ψ S = surface potential, n int = surface state density, Q int = charge density in the gate area,) is the governing factor for creating surface bands leading to the conduction of current. 47…”

Highly Efficient Room-Temperature Gas Sensor Based on TiO2Nanotube-Reduced Graphene-Oxide Hybrid Device

“…In addition, these junctions can be considered as the one sided abrupt junction (i.e. p-n ++ ;as N D (TiO 2 )>>N A (RGO) [6].Therefore, depletion layer mainly penetrates into the p-side (Wp>>Wn). With the exposure of reducing species (methanol, in this case), methanol donates electrons to the TiO 2 NT-RGO, therefore, the hole-depletion region (at RGO side) expands, and electron-depletion region (at TiO 2 NT side) reduces [8,24].…”

“…Therefore, the current state of development is geared to a synergistic hybridization of different categories of sensing elements and to reach a physiochemical optimum in gas-sensing performance. These hybrid structures not only retain the advantages of the constituting gas-sensing elements, but also, bring forth additional novel properties due to synergistic effects, summarized as follows :(i) RGO acts as a highly efficient (due to high mobility) conducting support between neighboring TiO 2 NTs and thus provide a continuous path for carrier transport from gas-interaction sites (mostly on metal oxides) to the collecting electrodes and (ii) the combination of p-type RGO and n-type metal oxides create a localized p-n junction which can be used to modulate the space-charge layers at the interfaces [1-2, [6][7][8][9][10][11][12][13][14]. In this study, TiO 2 NTs-RGO hybrid device was fabricated by a two-step electrochemical process and gas-sensing performance of the device was tested with methanol (in the concentration range of 10-800 ppm) as a test species.…”