Efficiency enhancement in GaN-based blue to blue-violet LDs by engineered nitride-oxide ohmic contacts (OxyGaN)

Project title

Name of Beneficiary/Beneficiaries

Łukasiewicz Research Network – Institute of Microelectronics and Photonics (Coordinator),
Institute of High Pressure Physics of the Polish Academy of Sciences,
TOP-GAN sp. z o.o.,
Technion (Israel),
Institute for Technical Physics and Materials Science HUN-REN Energy Research Centre (Hungary)

Name of programme

International programmes

Competition

M-era.net 2019

Project value

EUR 509,000.00, including the Polish part: PLN 1,290,658.00

Funding value

EUR 489,000.00, including the Polish part: PLN 1,204,900.00

Project delivery period

from 1 June 2020 to 31 September 2023

See the results of our work

Legenda:

Struktura DL – LD structure

DL zamontowana w obudowie – LD mounted in a casing

Demonstrator DL – LD demonstrator

Emisja światła z DL – LD light emission

What problem does our project solve?

The OxyGaN project aimed to enhance the efficiency of laser diodes (LDs) based on gallium nitride (GaN), which emit blue and blue-violet light. As LDs operate at high current densities, the main challenge lies in achieving low resistance and thermal stability in ohmic contacts, which act as communication bridges between the LD’s active region and the external circuit. Inspired by the structural, optical, and thermal similarities between GaN and ZnO, we developed a new type of ohmic contact using transparent conductive aluminium-doped zinc oxide (AZO).

Current metalised contacts used in LDs lack long-term stability and generate optical losses. Implementing oxide-based contacts developed during the project reduced device degradation after 100 hours of continuous operation at stabilised optical power compared to standard metallic contacts. Using AZO contacts on both sides of the LD structure enabled the creation of a better-performing device using a single cost-effective material, replacing previously used metallic contacts.

Additionally, the most commonly used transparent conductive oxide, indium tin oxide (ITO), relies on the rare element indium. Developing a functional technology based solely on AZO, which contains abundant elements, represents a significant step toward achieving sustainable development.

Who will benefit from the project's results?

The developed technology for stable and transparent contacts will enable resource-efficient and more energy-efficient laser diodes for industries such as automotive, display technology, welding, and calibration at reduced costs. This contact technology can be applied not only in optoelectronics, but also in high-power electronic devices based on GaN. Knowledge generated through the project, disseminated via peer-reviewed journal publications, will contribute to advancing contact technology for optoelectronic and electronic devices based on GaN.

The developed AZO thin conductive layer technology may also find applications in transparent displays, infrared filters, or transparent heaters for windows.

What was the biggest challenge for us in implementing the project?

The ambitious nature of the project and the challenges of both scientific and technological complexity required to achieve functional laser diodes often demanded greater efforts than initially planned. As a result, one major challenge was the continuous publication of scientifically significant project results in peer-reviewed journals.