Coherent light emission and electrical tuning of WS2-WSe2 interlayer excitons

Coherent on-chip light sources are essential components for integrated photonics, enabling interference-based logic, high-fidelity signal routing, and precision sensing. Two-dimensional (2D) materials offer a promising platform for realizing ultracompact light sources because they combine strong excitonic effects, broad material compatibility, and efficient electrical tunability. However, achieving simultaneous optical performance and stable electrical controllability is hindered by cavity geometry and electrode-induced optical losses. Here, we introduce a hybrid hexagonal boron nitride (hBN)–silicon nitride (Si3N4) photonic crystal cavity coupled to a WS2–WSe2 heterobilayer. The system features high-Q optical modes and provides robust electrical integration. We demonstrate coherent light emission from cavity-coupled WS2–WSe2 interlayer excitons, with coherence lengths exceeding 5 mm, the size of a typical photonic integrated circuit. Furthermore, by integrating MoS2 as low-loss electrodes, we show that the exciton emission can be spectrally tuned and brought in resonance with the cavity mode, without deteriorating its quality factor (Q > 1200). The combination of our hybrid cavity design with low-loss electrodes is a promising platform for on-chip light sources and 2D optoelectronics.