Bendable InGaN Light-Emitting Nanomembranes with Tunable Emission Wavelength

The integration of light-emitting diodes (LEDs) into the flexible devices has exhibited a great potential in the next-generation consumer electronics. In this study, we have demonstrated an exfoliated InGaN nanomembrane LED (NM-LED) separated from a GaN/sapphire substrate through an electrochemically wet etching process. The peak wavelengths blue-shifted phenomenon of the photoluminescence (PL) and the electroluminescence spectra were observed on the free-standing NM-LED compared to the nontreated LED with the same structure, which can be ascribed to the partial strain relaxation of the LED structure confirmed by the Raman spectra and the X-ray diffraction curves. A small divergent angle of the PL emission light has also been observed on the NM-LED. Moreover, the peak emission wavelength of this NM-LED can be even modulated from a red shift (521.7 nm) to a blue shift (500.4 nm) compared with that of the flat state (509.4 nm) while being curved convexly from top p-GaN:Mg side to bottom n-GaN:Si side. Our study provides an elegant way to develop a bendable light source with variable emission wavelengths through the mechanical deformation method.