Switchable optoelectronic performance in bilayer WSe2 homojunctions with alternating AA-AB stacking

Abstract

Lateral homojunction construction in two-dimensional (2D) semiconductors is critical for tailoring material properties to advance high-performance optoelectronics. In this study, a bilayer tungsten selenide (WSe2) homojunction with alternating AA-AB stacking was grown by one-step chemical vapor deposition. The resulting homojunctions, composed of hexagonal and triangular domains, exhibit unique mixed stacking configurations and distinct charge transfer behaviors. Notably, Raman and second-harmonic-generation (SHG) mapping revealed a periodic enhancement pattern in Raman signals and a characteristic “bright–dark–bright–dark” SHG intensity cycle, attributed to the unique stacking configuration. This distinctive pattern presents significant potential for the development of all-optical storage devices encoded with specific stacking states, offering promising prospects for both the fundamental research and practical applications of specially stacked 2D homojunctions.