High Responsivity and Wavelength Selectivity of GaN-Based Resonant Cavity Photodiodes

The implementation of blue-light photodiodes based on InGaN in emerging technologies, such as free-space visible light communication (VLC), requires transformative approaches toward enhanced performance, miniaturization, and integration beyond current Si-based technologies. This work reports on the design and realization of high-performance InGaN-based resonant cavity photodiodes with high-reflectivity lateral porous GaN distributed Bragg reflectors. The well-controlled porosification of GaN on the 2-inch wafers enables design and fabrication of optical components, unlocking the potential of nitride semiconductors for several applications. These resonant-cavity-enhanced photodiodes, which have a 12 nm-thick optically active region, exhibit a high responsivity (≈0.1 A W⁻¹) to blue-light even without any externally applied voltage. Furthermore, the device can operate as both an emitter and a detector of visible light at well-defined wavelengths with spectral overlap between the electroluminescence emission and photocurrent responsivity, meeting the requirement of wavelength selectivity, thermal stability, and low-power consumption for VLC, with potential for integration of different functionalities, that is, light emission and detection, on a single chip without additional light filters.