Palladium-Based Contacts on p-GaN and Their Application in Laser Diodes

Levchenko, Iryna; Kryvyi, Serhii; Kamińska, Eliana; Grzanka, Szymon; Grzanka, Ewa; Marona, Łucja; Perlin, Piotr

doi:10.3390/ma16196568

Open AccessArticle

Palladium-Based Contacts on p-GaN and Their Application in Laser Diodes

by

Iryna Levchenko

^1,*

,

Serhii Kryvyi

^2,3,

Eliana Kamińska

¹

,

Szymon Grzanka

¹,

Ewa Grzanka

¹,

Łucja Marona

¹ and

Piotr Perlin

¹

Institute of High Pressures Physics, Polish Academy of Sciences, 01-142 Warsaw, Poland

²

Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland

³

Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR 72701, USA

^*

Author to whom correspondence should be addressed.

Materials 2023, 16(19), 6568; https://doi.org/10.3390/ma16196568

Submission received: 29 August 2023 / Revised: 27 September 2023 / Accepted: 3 October 2023 / Published: 6 October 2023

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Abstract

In this paper, we investigate the effect of Pd thickness and heat treatment on Pd/Ni/Au/p-GaN metal contacts. The as-deposited samples exhibit a smooth morphology and non-linear I–V characteristics. Heat treatment in a N₂ atmosphere leads to degradation of the contact microstructure, resulting in diffusion of Ga, void formation on the interface and mixing of metals. Annealing in a mixture of N₂ and O₂ improves adhesion and reduces contact resistance. However, this process also induces GaN decomposition and species mixing. The mixing of metal–Ga and metal–metal remains unaffected by the method of thermal treatment but depends on gas composition for thin Pd contacts. To achieve low-resistance contacts (≈1 × 10⁻⁴ Ω cm²), we found that increasing the Pd thickness and using N₂ + O₂ as the annealing environment are effective measures. Nevertheless, the degradation effect of the annealed contact microstructure in the form of the void generation becomes evident as the thickness of Pd increases. Laser diodes (LDs) with optimized palladium-based contacts operate at a voltage of 4.1 V and a current density of 3.3 kA/cm².

Keywords: gallium nitride (GaN); thermal evaporation; solid-state solution; diffusion; palladium (Pd); nickel (Ni); gold (Au); ohmic contact; specific contact resistance (ρ); laser diode (LD)

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MDPI and ACS Style

Levchenko, I.; Kryvyi, S.; Kamińska, E.; Grzanka, S.; Grzanka, E.; Marona, Ł.; Perlin, P. Palladium-Based Contacts on p-GaN and Their Application in Laser Diodes. Materials 2023, 16, 6568. https://doi.org/10.3390/ma16196568

AMA Style

Levchenko I, Kryvyi S, Kamińska E, Grzanka S, Grzanka E, Marona Ł, Perlin P. Palladium-Based Contacts on p-GaN and Their Application in Laser Diodes. Materials. 2023; 16(19):6568. https://doi.org/10.3390/ma16196568

Chicago/Turabian Style

Levchenko, Iryna, Serhii Kryvyi, Eliana Kamińska, Szymon Grzanka, Ewa Grzanka, Łucja Marona, and Piotr Perlin. 2023. "Palladium-Based Contacts on p-GaN and Their Application in Laser Diodes" Materials 16, no. 19: 6568. https://doi.org/10.3390/ma16196568

APA Style

Levchenko, I., Kryvyi, S., Kamińska, E., Grzanka, S., Grzanka, E., Marona, Ł., & Perlin, P. (2023). Palladium-Based Contacts on p-GaN and Their Application in Laser Diodes. Materials, 16(19), 6568. https://doi.org/10.3390/ma16196568

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

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Palladium-Based Contacts on p-GaN and Their Application in Laser Diodes

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