交流驱动无电学接触GaN基Micro⁃LED器件光电特性

Photoelectric Characteristics of AC-driven Non-electrical Contact GaN-based Micro-LED Device

针对Micro‐LED器件微型化带来的尺寸效应、高速巨量转移、发光器件与驱动背板的高精度键合等问题,本文通过金属有机化学气相沉积和原子层沉积技术制备了一种垂直结构的交流驱动无电学接触型GaN基Micro‐LED器件,研究了其光电特性。结果表明,器件电路模型可等效为RC电路,随着交流驱动信号频率的增大,器件等效阻抗先快速减小后趋于稳定。当频率固定时,器件I⁃V特性呈线性关系,器件等效阻抗稳定,器件亮度随着驱动电压增大而增强。当驱动电压固定时,器件在16~22 MHz频率范围内达到最大亮度,且亮度随频率增加呈现先上升后下降趋势;此外,由于回路呈电容特性,无电学接触型Micro‐LED器件存在发光延迟效应和电流超前效应。对比传统Micro‐LED器件,无电学接触型Micro‐LED器件与外部电极无电学接触,在交流驱动条件下实现内部载流子复合发光,有望解决Micro‐LED芯片微型化带来的技术难题。

The miniaturization of Micro-LED devices presents a series of challenges,including size effects,highspeed mass transfer,and high-density bonding between light-emitting devices and driving backplanes.In this paper,an alternating current(AC)-driven non-electric contact(NEC)GaN-based Micro-LED device was prepared by metal organic chemical vapor deposition(MOCVD)and atomic layer deposition(ALD)and its photoelectric characteristics were also investigated.The results indicate that the circuit model of NEC Micro-LED devices can be represented by an equivalent RC circuit.The equivalent impedance initially decreases rapidly and then stabilizes with increasing AC-driven signal frequency.When the signal frequency keeps constant,the current-voltage(I⁃V)curves exhibit linear relationships and the equivalent impedance remains stable.The luminance increases continuously with increasing working voltage.When the driving voltage remains constant,the luminance of the device initially rises and then falls with the gradual increase in frequency,reaching a maximum luminance in the frequency range of 16-22 MHz.Additionally,the luminescence of the device is delayed and there is a current leading effect due to the capacitive property of the circuit.Compared with the traditional Micro-LED devices,the NEC Micro-LED devices have non-electrical contact with external electrodes and the luminescence of devices is attributed to inherent charge carriers un‐der AC driving conditions.This development offers a promising solution to the technical challenges from the miniatur‐ization of Micro-LED devices.