• Castellanos-Gomez, Andres
• Taniguchi, Takashi
• Ares, Jose R.
• Frisenda, Riccardo
• Ferrer, Isabel J.
• Lara, David Perez De
• Ghasemi, Foad
• Sánchez, Carlos
• Zant, Herre S. J. Van Der
• Papadopoulos, Nikos
• Flores, Eduardo
• Watanabe, Kenji
• Biele, Robert
• Dagosta, Roberto

Abstract

<p>In two-dimensional materials research, oxidation is usually considered as a common source for the degradation of electronic and optoelectronic devices or even device failure. However, in some cases a controlled oxidation can open the possibility to widely tune the band structure of 2D materials. In particular, we demonstrate the controlled oxidation of titanium trisulfide (TiS₃), a layered semicon-ductor that has attracted much attention recently thanks to its quasi-1D electronic and optoelectron-ic properties and its direct bandgap of 1.1 eV. Heating TiS₃ in air above 300 °C gradually converts it into TiO₂, a semiconductor with a wide bandgap of 3.2 eV with applications in photo-electrochemistry and catalysis. In this work, we investigate the controlled thermal oxidation of indi-vidual TiS₃ nanoribbons and its influence on the optoelectronic properties of TiS₃-based photodetec-tors. We observe a step-wise change in the cut-off wavelength from its pristine value ~1000 nm to 450 nm after subjecting the TiS₃ devices to subsequent thermal treatment cycles. Ab-initio and many-body calculations confirm an increase in the bandgap of titanium oxysulfide (TiO₂-xSx) when in-creasing the amount of oxygen and reducing the amount of sulfur.</p>

Topics

• impedance spectroscopy
• Oxygen
• semiconductor
• layered
• titanium
• two-dimensional
• band structure
• ion chromatography