Low dark current metal-semiconductor-metal ultraviolet photodetectors based on sol-gel-derived TiO2 films

Abstract

Natural Science Foundation of Fujian Province [2009J05151]The titanium dioxide (TiO2) films prepared by sol-gel processing were used to fabricate metal-semiconductor-metal ultraviolet photodetectors. A very low dark current of 5.38 pA (current density of 3.84 nA/cm(2)) at 5 V bias is obtained, which is ascribed to the high effective Schottky barrier between Au and TiO2 films. The x-ray photoelectron spectroscopy analysis demonstrates that the concentration of oxygen vacancies is very low in the surface of the TiO2 films, which is responsible for the high effective Schottky barrier. The devices exhibit a cutoff wavelength at about 380 nm and a large UV-to-visible rejection ratio (340 versus 400 nm) of three orders of magnitude. The peak responsivity of the devices is 17.5 A/W at 5 V bias, indicating the presence of internal photoconductive gain induced by desorption of oxygen on the TiO2 surface. (C) 2011 American Institute of Physics. [doi:10.1063/1.3537918

Photoresponse comparison of indium oxide (In₂O₃) nanomaterials

“…The lower dark current of the PVA coated photodetector is likely attributed to the change of the Schottky barrier height between the interface of Al and In 2 O 3 nanoparticles, as shown in Figure 5 (a). According to the conventional description of the Schottky UV detector, dark I-V characteristics in the thermionic-field emission regime follow the known relation [26,27]:…”

Pulse laser deposition of epitaxial TiO 2 thin films for high-performance ultraviolet photodetectors

“…Since the high quality TiO 2 films is essential for high-performance UV photodetectors, many techniques have been employed to prepare these high-quality TiO 2 films, including pulsed laser deposition (PLD) [5][6][7], magnetron sputtering [8][9][10], atomic layer deposition [11,12] and sol-gel method [13,14]. Our group recently demonstrated the growth of polycrystalline TiO 2 films by magnetron sputtering and sol-gel method for UV photodetectors [15,16]. As compared to other epitaxial wide bandgap semiconductors, such as SiC, GaN and ZnO, etc.…”

Photoelectron Properties of Nanocrystalline TiO2 Films Prepared by a Powerful Hydrothermal Technique

“…In the UV detecting field, TiO 2 has been proved to be insensitive to visible light but highly sensitive in the UV region and this characteristic makes it a good candidate in fabricating UV detectors . Recently, the TiO 2 ‐based UV detectors have obtained increasing attention owing to their superior chemical durability and thermo stability, low cost, compact size which makes them suitable for integration and further for large‐scale fabrication . Meanwhile, many good properties such as high sensitivity (889.6 A/W under 260 nm UV light), low dark current (9.73 pA at 5 V bias), have also been achieved in TiO 2 ‐based UV photodetectors.…”