摘要
通过环形传输线方法(CTLM),电流-电压(I-V)曲线、光学透过率、表面形貌等手段,研究了N i层厚度和N i层的高温退火对N i/ITO与p型氮化镓接触特性的影响,探讨了N i/ITO-p-GaN欧姆接触的形成机制,提出了低温氧化N i金属层的方法。获得接触电阻率(cρ)小于9.5×10-5Ω.cm2,透过率达到74%(470 nm)的N i/ITO-p-GaN电极。
Ni layer thickness and Ni layer annealing process which affect Ni/ITO-p-GaN ohmic contact were studied through CTLM, I-V curve, surface morphology, optical data etc. It was found that the Ni layer can help the formation of ohmic contact for ITO/GaN, and the contact resistance reduced at first and then increased with the thickness of Ni layer. The best ohmic contact electrode was got with Ni layer thickness of 6 nm, while the contact resistance of Ni/ITO on p-GaN was 9.5 × 10^-5 Ω@cm^2 and the transmittance could reach 74% at 470 nm. This result without high temperature annealing indicated that too much thick of Ni layer is bad for the formation of NiO, which could be related to low-resistance ohmic contact. How the Ni layer affect ohmic contact through annealing to Ni layer directly at oxide atmosphere was studied. The experiment showed that the contact resistances increase with annealing temperature. The NiO could be helpful to the formation for ohmic contact. But if the intermediate semiconductor layer （ISL） can＇t reduce the Schottky barrier height （SBH） of Ni/GaN interface much, the contact resistance will increase. It is easy for carrier injection where there is Ni atom, which can promote the character of ohmic contact better. According to the experiment resuits, a new method named low temperature （L-T） oxided Ni layer was proposed. This method can reduce ohmic contact resistance, better surface morphology and improve reliability of LED device.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2005年第6期757-760,共4页
Chinese Journal of Luminescence
基金
深圳市科技计划项目(2002-K1-65)
广东省关键领域重点突破(2B2003A107)资助项目
