A Novel Reactive Element Doping Strategy for Metal Oxides Using Pulsed Laser Deposition: Demonstration with Sulphur in VO2

Vanadium dioxide (VO 2 ) is a phase transition material with significant potential for applications in electrical and optical devices, owing to its remarkable properties such as a sharp change in resistivity and infrared transmittance during the phase transition. Lowering the transition temperature (T c ) while maintaining a high transition amplitude is crucial to many applications; however, conventional doping elements often compromise its transition amplitude. Recent simulations suggest that chalcogen doping, particularly with sulphur, could effectively tune T c without diminishing the transition performance. Sulphur doping, however, poses challenges due to the tendency of sulphur to react with oxygen during VO 2 's high-temperature deposition process, forming volatile sulphur oxides that are lost in the vacuum system. This study introduces a novel sulphur doping approach for VO 2 by using pulsed-laser deposition (PLD) from a V 2 S 3 target. By varying the laser repetition rate, sulphur incorporation was precisely controlled without inducing significant defects. Sulphur doping reduced T c by up to 44.3 °C/at.%, one of the most efficient reductions reported. However, higher sulphur concentrations led to reduced