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Name of experiment：study on photoelectric characteristics of non-conductor contact μLED devices

Research direction：AC LED drivers, semiconductor devices

Experiment content：

According to the model of non-conductor contact μLED, the corresponding device was prepared. Secondly, the frequency - voltage, current - voltage, luminescence intensity and other photoelectric characteristics of μLED driven by AC signal are studied.

GaN based microlight-emitting diodes (μLEDs) have outstanding advantages in ultra-high resolution display, micro display, visible light communication and solid state lighting. The mechanism of traditional μLED is: the hole electrons are injected from the P region and n region into the multi-quantum well respectively when the forward voltage is applied. Under forward bias, continuous electrons and holes are injected from the external electrode, resulting in continuous electron luminescence.

Purpose of experiment：

A non-conductor contact μLED model was established and its working mechanism was revealed, which provides theoretical guidance for improving the structure of μLED devices and optimizing the working mode.

Test equipment：

non-conductor contact μLED device, signal generator, power amplifier, optical power meter, avalanche photodetector, oscilloscope

Experimental process：

The voltage signals of different frequencies are generated by the signal generator, which are input to the power amplifier for amplification and output. The voltage signals are applied to the non-conductor contact μLED device. The electrical characteristics are tested by oscilloscope, and the electroluminescence characteristics are tested by optical power meter and avalanche photodetector.

Result of experiment： 

1. Driven by ac electric field, the μLED can be lit wirelessly without external charge injection.

2. A NEC&NCI model is proposed, which is related to the periodic oscillation of carriers under the action of alternating electric field. The model is further verified by experiments using a 'carrier pump' to achieve high optical power density.

3. The self-protection mechanism of the μLED device in capacitor is briefly discussed, that is, the μLED device can work normally under high voltage drive and prevent electric breakdown.