Monolithic Integration of GaN-Based Green Micro-LED and Quasi-Vertical MOSFET Utilizing a Hybrid Tunnel Junction

Abstract

We demonstrated the monolithic integration of GaN-based driving metal-oxide-semiconductor field effect transistor (MOSFET) on micro-light-emitting diodes (μLEDs) by regrowing a hybrid tunnel junction (TJ) on top of a commercial green LED wafer. The hybrid TJ served not only as the current spreading layer for μLEDs, but the n/p/n structure of the LED + TJ stack could also be utilized for fabricating a quasi-vertical driving MOSFET. The μLED was connected to the MOSFET via the conductive n-GaN layer. By modulating the gate supply voltage, the MOSFET effectively controlled the injection current of the μLED, allowing for precise modulation of its output performance. The integrated 60-μm μLED exhibited a high output power of 0.12 mW (~ 4.2 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) at a current of 0.3 mA (around 10 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) when the MOSFET was modulated with V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> = 5 V and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> = 16 V, demonstrating good μLED performance and comparable driving capability to previous GaN-based MOSFETs and oxide-based thin film transistors. This work provides a new method for GaN FET/LED monolithic integration, which paves the way for potential applications in visible light communication and flexible μLED displays.