Bismuth as a buffer layer for metal contact with silicon carbide studied by In situ photoelectron spectroscopy

IF 2.1 4区 化学 Q3 CHEMISTRY, PHYSICAL
Xiangrui Geng , Yishui Ding , Sisheng Duan , Wei Chen
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Abstract

Silicon carbide (SiC) is a promising third-generation semiconductor due to its wide bandgap. However, the high Schottky barrier and metal-induced gap states (MIGS) at the metal/SiC interface present significant challenges for device fabrication, leading to high contact resistance and poor current delivery. This study proposes the use of bismuth (Bi), with its semimetallic properties and gap-state saturation effect, as a contact buffer layer to address these issues. We conducted a systematic investigation of the chemical and electronic characteristics of the Pt/Bi/4H-SiC(0001) system, fabricated via molecular beam epitaxy (MBE), using in situ X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Our findings reveal weak bonding between the Bi buffer layer and the 4H-SiC(0001) surface, resulting in a slight downward band bending effect and the formation of a substantial dipole across the Bi/4H-SiC(0001) interface. Moreover, UPS spectra indicate a reduction in the work function of Pt/Bi/4H-SiC(0001), suggesting the potential for achieving low contact resistance. Notably, the Pt/Bi/4H-SiC(0001) system remains stable when exposed to 1.6×109 Langmuir of oxygen at room temperature, while a bare Bi buffer layer undergoes partial oxidation. These results provide a comprehensive understanding of the Pt/Bi/4H-SiC(0001) interfaces and strategies for improving metal/SiC contacts.

Abstract Image

通过原位光电子能谱研究铋作为金属与碳化硅接触的缓冲层
碳化硅(SiC)因其宽带隙而成为前景广阔的第三代半导体。然而,金属/碳化硅界面上的高肖特基势垒和金属诱导间隙态(MIGS)给器件制造带来了巨大挑战,导致接触电阻大、电流传输差。本研究提出使用具有半金属特性和间隙态饱和效应的铋(Bi)作为接触缓冲层来解决这些问题。我们利用原位 X 射线光电子能谱 (XPS) 和紫外光电子能谱 (UPS) 对通过分子束外延 (MBE) 制造的 Pt/Bi/4H-SiC(0001) 系统的化学和电子特性进行了系统研究。我们的研究结果表明,铋缓冲层和 4H-SiC(0001) 表面之间的结合力很弱,导致了轻微的向下带弯曲效应,并在铋/4H-SiC(0001) 界面上形成了大量偶极子。此外,UPS 光谱显示,Pt/Bi/4H-SiC(0001) 的功函数有所降低,这表明它具有实现低接触电阻的潜力。值得注意的是,Pt/Bi/4H-SiC(0001) 系统在室温下暴露于 1.6×109 朗缪尔氧时保持稳定,而裸铋缓冲层则会发生部分氧化。这些结果提供了对 Pt/Bi/4H-SiC(0001) 界面的全面了解,以及改进金属/SiC 接触的策略。
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来源期刊
Surface Science
Surface Science 化学-物理:凝聚态物理
CiteScore
3.30
自引率
5.30%
发文量
137
审稿时长
25 days
期刊介绍: Surface Science is devoted to elucidating the fundamental aspects of chemistry and physics occurring at a wide range of surfaces and interfaces and to disseminating this knowledge fast. The journal welcomes a broad spectrum of topics, including but not limited to: • model systems (e.g. in Ultra High Vacuum) under well-controlled reactive conditions • nanoscale science and engineering, including manipulation of matter at the atomic/molecular scale and assembly phenomena • reactivity of surfaces as related to various applied areas including heterogeneous catalysis, chemistry at electrified interfaces, and semiconductors functionalization • phenomena at interfaces relevant to energy storage and conversion, and fuels production and utilization • surface reactivity for environmental protection and pollution remediation • interactions at surfaces of soft matter, including polymers and biomaterials. Both experimental and theoretical work, including modeling, is within the scope of the journal. Work published in Surface Science reaches a wide readership, from chemistry and physics to biology and materials science and engineering, providing an excellent forum for cross-fertilization of ideas and broad dissemination of scientific discoveries.
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