In situ growth of Cu-doped MoS2 thin films via a laser-induced technique: efficient P-type doping and effective enhancement of the FET device performance†

Abstract

Molybdenum disulfide (MoS₂) is considered a potential material for next-generation optoelectronic devices owing to its tunable bandgap and high carrier mobility. A pulsed laser-induced technology can rapidly synthesize centimeter-scale MoS₂ films with high crystal quality at room temperature, making them compatible with complementary metal-oxide-semiconductor (CMOS) processes. Usually, the MoS₂ thin films that are prepared belong to n-type. However, to promote the application of pulsed laser-induced technology in two-dimensional material devices and circuits, achieving effective and uniform p-type doping is crucial. In this study, a novel in situ doping technique was proposed, wherein copper (Cu) was successfully doped into MoS₂ thin films as a p-type doping acceptor using pulsed laser-induced technology. The growth and doping processes were simultaneously completed. Raman spectra, high-resolution transmission electron microscopy (HRTEM) images and X-ray photoelectron spectroscopy (XPS) tests showed that Cu was successfully doped into the MoS₂ thin film with a uniform and effective doping effect. To further verify the p-type doping effect, back-gate field-effect transistors (FETs) were fabricated. Compared with the undoped one, the current on/off ratio of FET improved from 5 × 10² to 10⁵, and the field-effect mobility increased from 0.093 cm² V⁻¹ s⁻¹ to 16.05 cm² V⁻¹ s⁻¹. This indicated that the Cu doping of MoS₂ thin films effectively enhanced their conductivity and field-effect mobility. These findings demonstrate that pulsed laser-induced technology can achieve growth and in situ doping of MoS₂, improving both crystal quality and device performance, and it has the potential to be used in other element doping and two-dimensional (2D) materials.