7 May 2021

New integration concept for microLEDs

A new paper from the Centre for GaN Materials and Devices proposes a different type of integration concept for microLEDs – an epitaxial approach aiming to monolithically integrate μLEDs and high electron mobility transistors on a single chip.

MicroLED video display

A microdisplay (defined as an ultrasmall screen with <1 in. diagonal) is the key element for a wide range of next‐generation display systems such as augmented reality (AR), virtual reality (VR), helmet mounted displays (HMD) and head‐up displays (HUD) which are typically used in small spaces or at close proximity to the eye. As a result, high resolution, high luminance and a small form factor are essential.

Current liquid crystal on silicon or digital light processor based projection microdisplays cannot meet these requirements due to their intrinsic limitations (panel thickness, lifetime, flexibility) but a microdisplay based on III‐nitride inorganic semiconductor microLED (μLED) technologies has potential to eliminate these issues.

An epitaxial integration of μLEDs and high electron mobility transistors (HEMTs) that electrically drive individual μLEDs might be the ultimate approach to the fabrication of a microdisplay.

Recently, through an epitaxial growth approach to the formation of μLEDs on a pre‐patterned template we have demonstrated ultrasmall μLEDs with a record external quantum efficiency (EQE). In this paper, a different type of integration concept using an epitaxial approach is proposed, aiming to monolithically integrate μLEDs and high electron mobility transistors (HEMTs) on a single chip.

The proposed epitaxial integration concept is translated into a prototype, demonstrating an 8 × 8 microLED microdisplay, where each μLED is electrically driven by an individual HEMT which surrounds its respective μLED via the gate bias of the HEMT. Our 8 × 8 integrated μLEDs/HEMTs microdisplay is demonstrated through a short video showing “I ♥ Sheffield”.


Read the full paper in Advanced Materials Technologies.