Lateral Carrier Diffusion in Ion-Implanted Ultra-Small Blue III-Nitride MicroLEDs

Area of Science:

• Optoelectronics
• Semiconductor Devices
• Nanotechnology

Background:

• Ultrasmall micro-light-emitting diodes (μLEDs) below 10 μm are key for next-generation augmented reality (AR) and virtual reality (VR) devices.
• These devices offer high brightness and low power consumption, enhancing visual experience and device longevity.
• A significant challenge is the observed decrease in efficiency as μLED size reduces.

Purpose of the Study:

• To investigate the underlying mechanism of size-dependent efficiency reduction in ion-implanted μLEDs.
• To analyze the impact of lateral carrier diffusion on the performance of ultrasmall μLEDs.
• To understand how carrier behavior changes with decreasing μLED dimensions.

Main Methods:

• Fabrication of ion-implanted μLEDs with diameters of 10, 5, and 2 μm.
• Electroluminescence analysis using a Gaussian beam telescope to study light intensity profiles.
• Measurement of spatial carrier distribution and lateral diffusion length at varying current densities.

Main Results:

• Efficiency was observed to decrease with smaller μLED sizes, consistent with conventional etched μLEDs.
• Lateral carrier diffusion length was quantified, showing a decrease from 11.2 μm at 1 A/cm² to 2.4 μm at 1000 A/cm².
• The study confirmed that lateral carrier diffusion is the primary factor causing efficiency roll-off in smaller μLEDs.

Conclusions:

• Lateral carrier diffusion significantly impacts the efficiency of ultrasmall μLEDs.
• Understanding and mitigating lateral diffusion is crucial for optimizing μLEDs for AR/VR applications.
• Ion implantation provides a method to define μLED size without introducing nonradiative recombination centers.