High-performance p-type two-dimensional transistors enabled by weak disorder engineering

Abstract Two-dimensional (2D) field-effect transistors (FETs) have emerged as promising candidates to replace silicon FETs for next-generation low-power logic circuits. However, the performance of p-type 2D FETs remains far inferior to that of their n-type counterparts. High-performance FETs require both efficient charge doping and superior charge-transport properties, which have proven extremely challenging to achieve simultaneously in p-type 2D devices. Conventional substitutional impurity doping tends to introduce severe lattice damage and deep-level acceptor states in 2D semiconductors, which degrade carrier transport properties. Here, we demonstrate that weakly disordered 2D MoS2 and WS2 (denoted as WD-MS2)—fabricated via a two-step process involving sulfur vacancy generation followed by oxygen passivation—can enable both efficient hole doping and exceptional electronic transport properties. Photoelectron spectroscopy reveals that the Fermi level (EF) of WD-MS2 shifts downward by ~240 meV toward the valence band, accompanied by valence band tail broadening, owing to the weak disorder-induced shallow acceptor states. Structural characterizations confirm that WD-MS2 preserves an intact lattice structure. Raman spectroscopy further reveals the introduction of compressive strain, which may further enhance hole transport. Benefiting from the synergistic effects of efficient hole doping, preserved lattice integrity, and engineered compressive strain, the resulting p-type 2D WD-MoS2 and WD-WS2 FETs exhibit unprecedented performance, with exceptionally high field-effect hole mobilities (212 cm2 V-1 s-1 and 294 cm2 V-1 s-1), on/off current ratios (108 and 109), and large on-state current densities. Furthermore, p-type WD-WS2 FETs exhibit a subthreshold swing approaching the Boltzmann limit, enabling the demonstration of high-gain, low-power homogeneous 2D complementary metal-oxide-semiconductor (CMOS) inverters.