Levchenko Iryna, Kryvyi Serhii, Kamińska Eliana, Grzanka Szymon, Grzanka Ewa, Marona Łucja, Perlin Piotr
Institute of High Pressures Physics, Polish Academy of Sciences, 01-142 Warsaw, Poland.
Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland.
Materials (Basel). 2023 Oct 6;16(19):6568. doi: 10.3390/ma16196568.
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 N 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 N and O 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 Ω cm), we found that increasing the Pd thickness and using N + O 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.
在本文中，我们研究了钯（Pd）厚度和热处理对Pd/Ni/Au/p-GaN金属接触的影响。沉积态样品呈现出光滑的形貌和非线性的电流-电压（I-V）特性。在氮气（N）气氛中进行热处理会导致接触微结构退化，从而引起镓（Ga）扩散、界面处形成空洞以及金属混合。在N和O的混合气体中退火可改善附着力并降低接触电阻。然而，此过程也会引发氮化镓（GaN）分解和物种混合。金属-Ga和金属-金属的混合不受热处理方法的影响，但对于薄Pd接触而言，取决于气体成分。为了实现低电阻接触（≈1×10Ω·cm），我们发现增加Pd厚度并使用N+O作为退火环境是有效的措施。尽管如此，随着Pd厚度增加，以空洞产生形式出现的退火接触微结构退化效应变得明显。具有优化钯基接触的激光二极管（LD）在4.1V的电压和3.3kA/cm²的电流密度下工作。
