Optically Coupled Electrically Isolated, Monolithically Integrated Switch Using Al_xGa_1–xN/GaN High Electron Mobility Transistor Structures on Si (111)

In this article, we report on an optically coupled, electrically isolated switch based on the III-nitride heterostructures on a silicon substrate. All the circuit elements, including the ultraviolet (UV) detector and a normally on transistor, were monolithically integrated on a single AlxGa1–xN/GaN high electron mobility transistor (HEMT) stack grown on a 200 mm Si (111) substrate, and the process was fully compatible with conventional III-N HEMT fabrication flow. On-wafer UV detector was realized using a gate-recessed architecture which exhibited excellent spectral responsivity and broadband nature, while the discrete HEMT was found to exhibit ON current of 500 mA/mm. The integrated system was found to switch from an OFF-state current of 5 μA (UV-Off) to an ON-state current of 50 mA (UV-ON) in ∼4 ms, and this delay may be further reduced with optimization of such a monolithic device design and improvement of crystal quality of nitrides on the large area Si platforms.