Monolithically Integrated Metal/Semiconductor Tunnel Junction Nanowire Light-Emitting Diodes

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Gallium Nitride (GaN)-based nanowire light-emitting diodes (LEDs) are crucial for visible and deep ultraviolet (UV) applications.
• Conventional GaN tunnel junctions face challenges like stress, wide depletion regions, and light absorption, limiting device performance.

Purpose of the Study:

• To demonstrate a novel Al tunnel junction for p-contact-free InGaN/GaN nanowire LEDs.
• To evaluate the performance improvements offered by the Al tunnel junction compared to traditional designs.

Main Methods:

• Fabrication of n(++)-GaN/Al/p(++)-GaN backward diodes utilizing an epitaxial Al layer as the tunnel junction.
• Integration of the Al tunnel junction into InGaN/GaN nanowire LEDs.
• Characterization of electrical and optical properties of the fabricated LEDs.

Main Results:

• The developed p-contact-free nanowire LEDs exhibited a low turn-on voltage of approximately 2.9 V.
• Significant reduction in device resistance and enhancement in power output were observed compared to control devices.
• The Al tunnel junction effectively mitigated issues associated with conventional GaN tunnel junctions.

Conclusions:

• The Al tunnel junction is a promising alternative for overcoming critical challenges in GaN-based tunnel junction design.
• This approach enables the realization of low-resistivity, high-brightness III-nitride nanowire LEDs across visible and deep UV spectra.
• The monolithic integration of metal and semiconductor nanowire heterojunctions opens avenues for multifunctional nanoscale devices.