Heterogeneous Integration of Microscale GaN Light‐Emitting Diodes and Their Electrical, Optical, and Thermal Characteristics on Flexible Substrates

Materials and device strategies to form inorganic, thin‐film, microscale light‐emitting diodes (micro‐LEDs) are presented based on a simplified release method. High performance gallium nitride based blue micro‐LEDs are fabricated on and released from both patterned sapphire substrates (PSSs) and conventional nonpatterned sapphire substrates (CSSs). Micro‐LEDs are transferred onto copper and polyimide based flexible substrates and their electrical and optical performances are maintained. Thermal properties of PSS and CSS based micro‐LEDs are systematically explored on different substrates. Finally, micro‐LEDs combined with phosphor coatings demonstrate capability for polychromatic emission. The techniques presented here provide promising paths to advanced light sources with potential applications in lighting, displays, and biomedicine.