金属/多晶锗硅肖特基接触特性的影响因素研究

用射频磁控溅射在单晶硅上沉积Si1-xGex薄膜.溅射的SiGe薄膜样品,用俄歇电子谱(AES)测定其Ge含量,约为17％,即Si0.83Ge0.17.样品分别做高温磷、硼扩散,经XRD测试为多晶态,制得n,p-poly-Si0.83Gge0.17.在n-poly-Si0.83Ge0.17上分别溅射Ni、V、W、Cu、Pt、Ti、Al、Co膜,做成金属/n-poly-Si0.83Ge0.17肖特基结.利用Ⅰ-Ⅴ测试数据进行接触参数的提取,从而定量研究金属的功函数、金属膜厚以及快热退火温度对肖特基接触特性的影响.结果发现,肖特基势垒高度(SBH)与金属的功函数有微弱的正相关,Al/n,p-poly-Si0.83Ge0.17接触存在Shannon效应,金属膜厚对Co/n,p-poly-Si0.83Ge0.17接触特性有不同的影响,随快热退火温度的升高,Ni、V、W、Co、Cu、Pt、Ti、Al八种金属在n-poly-Si0.83Ge0.17上的肖特基势垒高度和理想因子未见有一致的变化规律,但存在不均匀性.     

金属与半导体肖特基接触势垒模型及其载流子传输机制的研究进展

肖特基结具有整流特性,在整流器和光电检测等电子元器件制造中有极其重要的应用,重点介绍了相关研究人员在金属与半导体肖特基接触势垒的形成机理、相关数学模型及其影响因素等方面的研究进展。有研究表明,肖特基势垒的形成主要是由于费米能级的钉扎,而费米能级钉扎则源于界面新相的形成或界面极化键的存在。同时,在肖特基势垒的相关模型中,热电子激发模型是目前应用最为广泛的、用于解释界面载流子传输机制的肖特基接触势垒模型。随着对接触界面载流子传输机制的深入研究,热发射-扩散、热场发射等载流子传输机制模型相继被研究者提出。另外,相关研究表明,快速退火处理可导致肖特基接触界面处的原子扩散、重排、新相生成等现象,对肖特基接触的稳定性产生重要影响。     

外加偏压对未退火Co/n-poly-SiGe肖特基接触特性的影响

采用直流离子束溅射法,在n型单晶硅衬底上淀积Si1-xGex薄膜.俄歇电子谱(AES)测得Si1-xGex薄膜的Ge含量约为0.15.对薄膜进行高温磷扩散后,经XRD测试为多晶态,即得n-poly-Si0.85Ge0.15.在n-poly-Si0.85Ge0.15上溅射一层薄的Co膜,做成Co/n-poly-Si085Ge0.15肖特基结样品.在90～332 K范围对未退火样品做I-V-T测试.研究发现,随着外加偏压增大,表观理想因子缓慢上升,肖特基势垒高度(SBH)下降.基于SBH的不均匀分布建模,得到了二者近似为线性负相关的结论.     

ZnO上肖特基接触的研究进展

由于ZnO存在本征施主缺陷(锌间隙和氧空位),使得表面存在较高浓度的施主能级,难以获得肖特基接触.本文回顾了近年来在n型ZnO上制备肖特基接触的研究进展,对n型ZnO上制备肖特基接触的Au、Pt、Pd、Ag等金属方案的性能与特点,以及影响接触性能等因素,如表面处理和退火等进行了分析与归纳.同时,对P型ZnO上难以获得肖特基接触的原因进行了讨论.另外,由于Au、Pt等金属普遍存在热稳定差的问题,会降低ZnO基大功率器件的寿命,寻找能与n型ZnO能形成高热稳定性、低泄露电流、高势垒高度的肖特基接触材料是未来ZnO上肖特基光电器件的发展方向.     

III族氮化物基的肖特基势垒二极管的研制

研制了三类不同金属和III族氮化物接触的肖特基势垒二极管。测量了器件的电流-电压特性，并分析了器件偏离理想情况的原因。     

肖特基型光催化剂研究进展

贵金属与半导体复合形成的催化剂具备肖特基结结构,该结构具有整流特性和较低的界面电压,可以调控光生电子的产生和流向,使电子和空穴更有效地分离,提升光催化性能。综述了近年来肖特基半导体光催化剂的研究进展,分析了晶面沉积、形貌结构、表面等离子体效应及共掺杂等因素对该类催化剂性能的影响,从降解污染物、制氢、二氧化碳还原等方面阐述了这类催化剂在环境控制领域的实际应用,并提出了势垒高度、产物控制及催化剂循环利用等潜在的研究方向。肖特基型光催化剂独特的性质将使其成为新的研究热点,得到更深入的研究和应用。     

金属-Bi2OS2界面肖特基势垒以及电荷转移机制研究(英文)

由于金属与二维半导体接触界面复杂的电荷转移,界面处经常会产生强烈的费米钉扎效应.本文以Bi₂OS₂(拥有目前二维半导体材料中已知的最高电子迁移率)作为二维沟道层,采用密度泛函理论系统地计算了其与金属电极接触界面的肖特基势垒以及界面电荷转移机制.当Bi₂OS₂与三维金属电极接触时,界面强的电荷转移主要由化学键的形成以及泡利电荷排斥作用引起,导致界面具有强的费米钉扎,并且由这两个原因引起的电荷转移方向相反.此外,当金属的功函数大于半导体的电离能或小于半导体的电子亲合能时,界面会产生一个额外的电荷转移.当Bi₂OS₂与二维金属电极接触时,界面的费米钉扎完全被抑制,界面遵循肖特基-莫特定律,这是因为本文所选用的二维金属电极能够有效地屏蔽泡利电荷排斥作用.因此,通过选择不同功函数的二维金属电极,能够宽范围、线性地调节界面的肖特基势垒高度,并且能够实现界面从n型欧姆接触到p型欧姆接触的转变.这项研究不仅为Bi₂OS₂基器件的...     

碳纳米管表面Co/MoSe2莫特-肖特基异质结的构筑及高效析氢性能(英文)

二硒化钼(MoSe₂)是一种先进的电解水制氢催化剂，但其电催化性能还远不如金属铂(Pt)。将半导体与金属结合构建莫特-肖特基异质结是一种提高催化活性的有效途径。本文采用溶胶-凝胶工艺和热还原法在碳纳米管表面制备了金属钴(Co)/半导体MoSe₂莫特-肖特基异质结(Co/MoSe₂@CNT)。实验和理论计算结果表明Co/MoSe₂莫特-肖特基异质结导致电子在界面处重新分布并形成一个内建电场，这不仅可以优化氢原子吸附的自由能，还可以提高析氢过程中电荷的传输效率。因此，Co/MoSe₂@CNT获得了优异的析氢活性：在电流密度为10 mA cm^-2时的过电势仅为185 mV、Tafel斜率为69 mV dec^-1。这项工作提供了一种新的策略来制备Co/MoSe₂莫特-肖特基异质结，并突出了莫特-肖特基效应的重要意义，有利于未来开发出更高效的莫特-肖特基电催化剂。     

肖特基型光催化剂研究进展

贵金属与半导体复合形成的催化剂具备肖特基结结构,该结构具有整流特性和较低的界面电压,可以调控光生电子的产生和流向,使电子和空穴更有效地分离,提升光催化性能.综述了近年来肖特基半导体光催化剂的研究进展,分析了晶面沉积、形貌结构、表面等离子体效应及共掺杂等因素对该类催化剂性能的影响,从降解污染物、制氢、二氧化碳还原等方面阐述了这类催化剂在环境控制领域的实际应用,并提出了势垒高度、产物控制及催化剂循环利用等潜在的研究方向.肖特基型光催化剂独特的性质将使其成为新的研究热点,得到更深入的研究和应用.     

具有等离子共振效应的纳米金属在光解水中的应用

简述光催化分解水反应的基本原理、肖特基结和等离子体共振的概念、等离子体共振在光解水过程的工作机制。介绍Au和Ag等贵金属复合半导体、单一银系化合物、非贵金属等离子体光催化剂。提出具有等离子共振效应的金属纳米颗粒能提高光解水性能的原因是形成肖特基结和具有独特的局域表面等离子共振效应;相比半导体,金属的功函数较大,形成的肖特基结可实现电荷定向迁移;局域表面等离子共振效应通过共振能量转移、增强局部场强和热电子注入等方式拓宽光谱吸收,提高电荷分离效率和光催化效率。认为等离子光催化的研究目前主要集中在Au、Ag等贵金属,其原理有待深入探究,且应理论与实验相结合;开发非贵金属替代物将更有利于降低成本。     

Temperature dependence of current—voltage characteristics of Au/n-GaAs epitaxial Schottky diode

The influence of temperature on current-voltage (I-V) characteristics of Au/n-GaAs Schottky diode formed on n-GaAs epitaxial layer grown by metal organic chemical vapour deposition technique has been investigated. The dopant concentration in the epitaxial layer is 1 X 10¹⁶ cm^-3. The change in various parameters of the diode like Schottky barrier height (SBH), ideality factor and reverse breakdown voltage as a function of temperature in the range 80–300 K is presented. The variation of apparent Schottky barrier height and ideality factor with temperature has been explained considering lateral inhomogeneities in the Schottky barrier height in nanometer scale lengths at the metal-semiconductor interface     

Post-annealing behavior of Ni/Au Schottky contact on non-polar a-plane GaN

The effects of annealing on the performance of Schottky devices on a-plane GaN/r-plane sapphire were investigated. The results show that the post-anneal Schottky barrier height (SBH) increased with increasing annealing temperature, reaching a peak increase of 43% at 500 °C. A further increase in the anneal temperature above 500 °C degraded the SBH. The ideality factor displayed a weak dependence on post-annealing temperature until rising dramatically at a post-annealing temperature of 600 °C. The degradation at 600 °C post-annealing temperature can be attributed to the formation of Nickel-Gallides. In-situ current-voltage characteristics obtained between 15 °C and 165 °C revealed that both the ideality factor and SBH were stable up to 165 °C with increasing in-situ measurement temperature.     

Supersensitive,Fast‐Response Nanowire Sensors by Using Schottky Contacts

A Schottky barrier can be formed at the interface between a metal electrode and a semiconductor. The current passing through the metal‐semiconductor contact is mainly controlled by the barrier height and barrier width. In conventional nanodevices, Schottky contacts are usually avoided in order to enhance the contribution made by the nanowires or nanotubes to the detected signal. We present a key idea of using the Schottky contact to achieve supersensitive and fast response nanowire‐based nanosensors. We have illustrated this idea on several platforms: UV sensors, biosensors, and gas sensors. The gigantic enhancement in sensitivity of up to 5 orders of magnitude shows that an effective usage of the Schottky contact can be very beneficial to the sensitivity of nanosensors.     

Photoelectron spectroscopic investigation of InN and InN/GaN heterostructures

The surface band diagram of InN and band structure of the InN/GaN interface were studied using ultraviolet photoemissive yield spectroscopy and X-ray photoemission spectroscopy (XPS). The surface work function and the difference between the Fermi level and the conduction band minimum of InN were determined by ultraviolet photoemissive yield measurement. The band offsets and surface band bending were determined using XPS. Both spectra proposed downward band bending of the InN surface. Moreover, the Schottky barrier height (SBH) of the InN/GaN interface is determined (1.5 eV). Comparison of the measured SBH with our previous results by electrical measurement is discussed. The physical quantities derived in this work provide important information for use in future studies of InN and InN/GaN heterostructures.     

Determination of the laterally homogeneous barrier height of metal/p-InP Schottky barrier diodes

We have reported a study of a number of metal/p-type InP (Cu, Au, Al, Sn, Pb, Ti, Zn) Schottky barrier diodes (SBDs). Each one diode has been identically prepared on p-InP under vacuum conditions with metal deposition. In Schottky diodes, the current transport occurs by thermionic emission over the Schottky barrier. The current–voltage characteristics of Schottky contacts are described by two fitting parameters such as effective barrier height and the ideality factor. Due to lateral inhomogeneities of the barrier height, both characteristic diode parameters differ from one diode to another. We have determined the lateral homogeneous barrier height of the SBDs from the linear relationship between experimental barrier heights and ideality factors that can be explained by lateral inhomogeneity of the barrier height. Furthermore, the barrier heights of metal–semiconductor contacts have been explained by the continuum of metal-induced gap states (MIGS). It has been seen that the laterally homogeneous barrier heights obtained from the experimental data of the metal/p-type InP Schottky contacts quantitatively confirm the predictions of the combination of the physical MIGS and the chemical electronegativity.     

Schottky contacts of refractory metal nitrides on gallium nitride using reactive sputtering

Schottky contacts of refractory metal nitrides formed by reactive sputtering on n-type gallium nitride (GaN) were electrically evaluated, including film resistivity, Schottky characteristics and thermal stability. For the metal nitrides of TiN_x, MoN_x and ZrN_x, resistivities of 108.3, 159.0 and 270.0 μΩcm were obtained, respectively. Current-voltage (I-V) characteristics showed that the ideality factor varied from 1.03 to 1.16, while the Schottky barrier height (SBH) varied from 0.66 to 0.79 eV for the three kinds of Schottky contacts. Especially for the ZrN_x contact, the ideality factor and SBH were improved after annealing at 800 °C for 30 s. Schottky contact utilizing a refractory metal nitride on GaN shows its potential to develop thermally stable GaN devices.     

Diode-Like Selective Enhancement of Carrier Transport through Metal–Semiconductor Interface Decorated by Monolayer Boron Nitride

2D semiconductors such as monolayer molybdenum disulfide (MoS₂) are promising material candidates for next-generation nanoelectronics. However, there are fundamental challenges related to their metal–semiconductor (MS) contacts, which limit the performance potential for practical device applications. In this work, 2D monolayer hexagonal boron nitride (h-BN) is exploited as an ultrathin decorating layer to form a metal–insulator–semiconductor (MIS) contact, and an innovative device architecture is designed as a platform to reveal a novel diode-like selective enhancement of the carrier transport through the MIS contact. The contact resistance is significantly reduced when the electrons are transported from the semiconductor to the metal, but is barely affected when the electrons are transported oppositely. A concept of carrier collection barrier is proposed to interpret this intriguing phenomenon as well as a negative Schottky barrier height obtained from temperature-dependent measurements, and the critical role of the collection barrier at the drain end is shown for the overall transistor performance.