Production of PtInx Thin Films by the Pulsed Laser Welding Technique

Abstract

Herein, PtInx nanosheets are fabricated by the pulsed laser welding technique (PLW) in an argon atmosphere within seconds from stacked layers of Pt (150 nm) and In (150 nm). Pt/In stacked layers coated by thermal evaporation under a vacuum pressure of 10−5 mbar are exposed to pulsed laser irradiation. During the welding process, the pulse width, repetition frequency and arc voltage of the laser are all varied. It is observed that the formed PtInx alloys are highly sensitive to the laser welding conditions. A new phase of PtInx alloys, referred to as PtIn4, is obtained and shown to favor a monoclinic crystal structure. PtIn4 displayed a high microwave cutoff frequency exceeding 100 GHz and negative capacitance effect. Modeling of the capacitance spectra in accordance with the Drude–Lorentz approach for ac conduction showed that converting stacked layers of Pt/In into thin films of PtIn4 form by PLW improves the electrical conductance and the drift mobility of the films. A 900-fold enhancement in mobility is achieved via the PLW technique. The characteristics of the produced PtIn4 thin films, including the negative capacitance (NC) effects and the cutoff frequency values, make the films attractive candidates for use as the active layer to produce NC thin film transistors and as band filters suitable for 6G technology.