Monolithically Integrated All-GaN 2T1C-μLED-PDs

Abstract We demonstrate a fully monolithic all-GaN platform that integrates micro-light-emitting diode (μLED) pixels, two-transistor-one-capacitor (2T1C) pixel circuits, and near-coupled photodiodes (PDs) into 2T1C-μLED-PD units. The integrated 2T1C-μLED-PDs operate simultaneously as microdisplay pixels and on-chip emitter-detector pairs, realizing a high-density multifunctional integration within an ultracompact footprint. The μLED pixels exhibit effective modulation in light intensity via the voltage signals applied to the monolithically integrated 2T1C pixel circuits, confirming the suitability of 2T1C-μLED-PDs in the field of microdisplays. Crucially, the PDs are fabricated from the identical μLED structures and placed immediately adjacent to the μLED pixels, enabling the direct on-chip optical coupling and efficiently converting the voltage-controlled light signals into photocurrent, without requiring external optics. The dual-function and fully monolithic 2T1C-μLED-PDs offer a scalable platform for highly integrated, multifunctional all-GaN optoelectronic systems.