Characterization of semi-polar (20[Formula: see text]1) InGaN microLEDs

Area of Science:

• Materials Science
• Solid State Physics
• Optoelectronics

Background:

• Indium Gallium Nitride (InGaN) based light-emitting diodes (LEDs) are crucial for solid-state lighting.
• Semi-polar crystal planes offer potential advantages over traditional c-plane orientations for InGaN LEDs.
• Understanding the impact of chip size on device performance is essential for optimizing LED efficiency.

Purpose of the Study:

• To fabricate and compare the performance of semi-polar (20[211]1) InGaN blue LEDs with c-plane LEDs.
• To investigate the influence of varying chip sizes on the electrical and optical characteristics of these LEDs.
• To determine the optimal chip size for maximizing output power density in semi-polar LEDs.

Main Methods:

• Fabrication of semi-polar (20[211]1) InGaN blue LEDs and c-plane InGaN blue LEDs.
• Performance characterization of LEDs with chip sizes including 100 μm × 100 μm, 75 μm × 75 μm, 25 μm × 25 μm, and 10 μm × 10 μm.
• Analysis of electrical properties (current density, forward voltage) and optical properties (output power density, internal quantum efficiency (IQE), blue-shift).

Main Results:

• Semi-polar LEDs exhibited different contact behavior compared to c-plane LEDs.
• Smaller chip sizes resulted in higher current density and lower forward voltage for semi-polar LEDs.
• The 25 μm × 25 μm semi-polar LED achieved the maximum output power density, while larger devices showed higher IQE at lower current densities with less droop compared to c-plane LEDs.

Conclusions:

• Chip size significantly impacts the performance of semi-polar InGaN LEDs, with smaller sizes generally improving current handling.
• The 25 μm × 25 μm chip size represents an optimal balance for maximizing output power density in semi-polar (20[211]1) InGaN blue LEDs.
• Semi-polar LEDs demonstrate potential for reduced efficiency droop and low blue-shift phenomena, offering advantages over c-plane devices.