The critical effect of the thickness of Ni film on the performance of the Ni/Au Ohmic contact to p-G

• 作 者: XJ Li DG Zhao DS Jiang
• 机 构: State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of
• 出 处: 第十四届全国固体薄膜学术会议
• 发表日期: 2014年8期

　　The critical effect of the thickness of Ni film on the performance of the ohmic contact of Ni/Au to p-GaN is studied.The Ni/Au metal films with thickness of 15/50 nm on p-GaN led to better electrical characteristics[1,2], showing a lower specific contact resistivity of1.7× 104Ω·cm2 after annealing in the presence of oxygen.Both the formation ofa NiO layer and evolution of the metal structure at the sample surface and at the interface with p-GaN were checked by transmission electron microscopy (TEM) and energy-dispersive x-ray spectroscopy(EDX).Further analyses indicate that suitable Ni thickness is good for the transformation from Ni to NiO and the optimal distribution of NiO and Au will be resulted during annealing in the presence of oxygen.The transformation brought about a specific relationship of crystal orientation between the crystalline NiO, Au islands, and p-GaN[3].When the crystalline NiO directly contacts to p-GaN, the barrier height decreases[4,5].However, too much NiO formed in the surface will deteriorate the electrical conductivity.Combining these effects, choosing a suitable thickness of Ni is critically important for low-resistance ohmic behavior of the p-type contact.