Wavelength-stable InGaN-based amber micro-LEDs.

InGaN-based long-wavelength micro-LEDs often exhibit a significant blue-shift in emission wavelength with increasing current density due to the pronounced quantum-confined Stark effect (QCSE), which limits their applicability in display technologies and visible light communication. In this study, we report the fabrication of InGaN amber micro-LEDs with a 40 μm pixel size, employing a thick InGaN film (bulk InGaN) as the active region instead of the conventional multiple quantum well (MQW) structure. The devices exhibit a minimal wavelength shift from 618 to 608 nm as the injection current increases from 5 to 5000 μA. This 10 nm shift over three orders of magnitude in current demonstrates excellent wavelength and color stability. These results highlight a promising approach to overcoming the challenge of spectral instability in long-wavelength micro-LEDs, enhancing their viability for high-performance display and communication applications.