Impact of Charge Carrier Transfer and Strain Relaxation on Red-Emitting InGaN/GaN Heterostructures

InGaN-based visible light-emitting devices (LEDs) with efficient and stable emission over a wide luminosity range are essential for next-generation display technologies. To date, however, InGaN-based red LEDs exhibit low efficiency and poor wavelength stability due to the presence of extensive defects, dislocations, and strain-induced quantum-confined Stark effect. Here, we report a unique charge carrier transfer process from c-plane InGaN to semipolar-plane InGaN formed spontaneously in nanowire heterostructures, which can effectively reduce the instantaneous charge carrier density in the active region, thereby leading to significantly enhanced emission efficiency in the deep red wavelength. Furthermore, we show that the total built-in electric field can be reduced to a few kV/cm by canceling the piezoelectric polarization with spontaneous polarization in strain-relaxed high indium composition InGaN/GaN heterostructures. We experimentally achieved an ultrastable red emission color in InGaN over 4 orders of magnitude of excitation power range. This work provides a vital method for addressing some of the fundamental issues in light-emitting devices and sheds light on designing high-efficiency and high-stability optoelectronic devices.