The OxyGaN project finished on 31.08.2023. It was a great adventure concerning the technology of oxide ohmic contacts for GaN-based laser diodes. We started with the ambition to provide simplified processing of GaN LDs by developing a technology of single-type oxide electrode forming contacts to both sides of the LD, i.e. the top p-type Ga-face GaN and the bottom n-type N-face GaN. To achieve this, bothe the engineering of the oxide and the interface between the oxide ang the nitride had to be undertaken. By doing the work planned in the project, we were able to achieve the following:
- developing better than state-of-the-art AZO films deposited at room temperature with record low resistivities. Room temperature deposition enables lift-off patterning;
- understanding the process of AZO band gap engineering by adding Mg using different sources: Mg and AZO targets as well as a single compound target;
- developing efficient p-type ohmic contact through ultrathin interlayer insertion at the interface, although the exact mechanism of contact formation is still puzzling;
- developing good ohmic contacts to n-type N-face GaN by interface processing and interlayer insertion;
- fabricating a fully packaged demonstrator diode at TRL 6 with all oxide contacts, the performance of which is better than reference diodes with classical metallic contacts, in terms of contact resistivity, threshold voltage, current stability after lifetime testing as well as lower degradation after 100 hours at constant optical power.
These achievements are the result of hours of hard work and scientific cooperation within the consortium. Standing collaboration has been established between the partners for future work in the area of nitride semiconductors. The results of the work have been presented over 25 times at national and international conferences and two patent applications were prepared. The strict shedule of the project left not much time for publications, so while two have been published, others are still waiting for final touches. What follows is a list of them, which will be updated in the future.
With thanks to our funding agencies and everyone responsible for the success of this project,
Michał Borysiewicz, OxyGaN coordinator,
Łukasiewicz Research Network – Institute of Microelectronics and Photonics
OxyGaN publications
- A. Wójcicka, Z. Fogarassy, A. Rácz, T. Kravchuk, G. Sobczak, M.A. Borysiewicz, „Multifactorial investigations of the deposition process – material property relationships of ZnO:Al thin films deposited by magnetron sputtering in pulsed DC, DC and RF modes using different targets for low resistance highly transparent films on unheated substrates”, Vacuum, 203 (2022) 111299 doi.org/10.1016/j.vacuum.2022.111299
- Z. Fogarassy, A. Wojcicka, I. Cora, A.S. Racz, S. Grzanka, E. Dodony, P. Perlin, M.A. Borysiewicz, „Structural and electrical investigation of Al/Ti/TiN/Au based N-face n-GaN contact stack”, Materials Science in Semiconductor Processing, 175 (2024) 108250 doi.org/10.1016/j.mssp.2024.108250
Project public reports