Chapter 5 metalsemiconductor compound contacts to nanowire. For example, good ohmic contacts are essential for achieving excellent electrical characteristics of a semiconductor device, while schottky i. Metal semiconductor ohmic contacts rcsd r dp rext rov x y 0 sidewall gate silicide nextx novy year 1997 1999 2003 2006 2009 2012 min feature size 0. Metal semiconductor contacts and devices 97801223417. Ohmic contacts common techniques to make ohmic contacts choose metal so that its work function fmetal is close to that of semiconductors fsemi thermal ionic insert thin layer of narrow bandgap material between metal and semiconductor increase the doping level near the semiconductor surface as high as possible tunneling assisted. Save up to 80% by choosing the etextbook option for isbn. The principle of forming different types of the metalsemiconductor contact is the mismatch of the fermi energy between metal and semiconductor material, which is due to the difference in work functions. To improve the contacts, the interface formed between metal and semiconductor during contact deposition must be better understood. Importance of metalsemiconductor contacts is due to l ohmic metalsemiconductor junctions e. B is significantly higher than the thermal energy kt, the semiconductor is depleted near the metal and behaves as a schottky barrier. The physics and technology of metal semiconductor interfaces are keypoints in the development of silicon carbide sic based devices. Metalsemiconductor ohmic contacts stanford university. The term metal silicon contact includes silicidesi contacts. Lecture 17 metalsemiconductor junction march 14, 2007 contents.
Metal semiconductor contacts and devices by simon s. Metal semiconductor contacts and devices, volume 1st. A monographs in electrical and electronic engineering rhoderick, e. Basically, there are two types of ms contacts that are widely used in semiconductor devices. Gold has a work function closely matching that of high resistivity cdznte and is a popular choice of contact metal. Current begins to flow from the semiconductor to the metal. Introduction metal semiconductor junctions a wide range of metals, such as silver ag, gold au, copper cu, aluminum al and alloys are used to make electrical contacts to semiconductors.
Most metalsemiconductor contacts are annealed or alloyed after the initial deposition of the metal in an effort to further improve the contact resistivity. The small barrier that exists for electron flow from metal to the semiconductor, but vanishes when. Perspectives from research on metalsemiconductor contacts. Unlimited viewing of the articlechapter pdf and any associated supplements and figures. Doitpoms tlp library introduction to semiconductors metal. Metallic contact between mos2 and ni via au nanoglue cover page pdf available in small 1422 may 2018 with 152 reads how we measure reads. E i e v e c e i b e f when the materials are brought into contact with one another, they are not in equilibrium e fs. Lecture 1 introduction to semiconductors and semiconductor. Us3983264a metalsemiconductor ohmic contacts and methods. Metalsemiconductor junctions barrier basics shorted metal and semiconductor in physical contact as the distance between the metal and semiconductor decreases to zero, the depletion region grows qf m e f qc s e e c qf b qf m qc s v the final depletion region width is that needed to support a potential change equal to the builtin. It is well known that the quality of metal semiconductor contacts plays an important role in the performance of various semiconductor devices and integrated circuits. Ohmic contacts to semiconductor surfaces are fabricated by a process which includes the formation of an adherent, uniform insulating film at the interface between the semiconductor surface and the metallization layer. Metalsemiconductor contacts monographs in electrical and electronic engineering rhoderick, e.
Chapter 3 260 ece 615 semiconductor devices i winter 2019 john labram announcements midterm i will return graded midterm examinations on thursday 14th february. A nonrectifying contact whose relationship between current and voltage has a low interfacial contact resistance r c, and is preferably linear, is referred to as an ohmic contact. The insulating film contains stationary charges of sign opposite to the sign of the conductivity of the semiconductor whereby image charges are. Metalsemiconductors contacts engineering libretexts. Gold contacts are often formed by electroless deposition however this forms a complex interface. Metalsemiconductor contacts serve as active or passive components in all semiconductor electronic devices such as diodes and fieldeffect transistors. Process engineers, device physicists, circuit designers, and students of this discipline will find the book very useful. This behavior is commonly used for creating metal contacts to the outside. The principle of forming different types of the metal semiconductor contact is the mismatch of the fermi energy between metal and semiconductor material, which is due to the difference in work functions. Introduction to metal semiconductor contacts sze and ng.
The model covers the entire range from schottky to ohmic contacts and fits well with experimental ivcharacteristics of intermediately doped silicon. In particular, a large mismatch between the fermi energy of the metal and semiconductor can result is a highresistance rectifying contact. The effect of interface states on the barrier heights of metal semiconductor contacts was first analyzed by cowley and sze 33. Metalsemiconductor contacts monographs in electrical and.
Figure 1 below shows a schematic of an ideal mosc device. Ideal metalsemiconductor contacts but the point of adding contacts was to apply fields, lets look at this m s metal semiconductor ntype apply positive bias, v v e v e c e i e fs current e fm this lowers e fm below e fs and reduces the barrier seen by electrons. Thus, optimizing the contacts between 2d semiconductors and metal electrodes is an important technological challenge. Introduction usually, in device simulation the physical system metal semiconductor ms interface. The general structure is a lightly doped ptype substrate, into which two regions, the source and the drain, both of heavily doped ntype semiconductor have been embedded. Although in the last decade, the metal to 4hsic contacts. Chapter 4 metalsemiconductor contacts and semiconductorsemiconductor heterojunctions 4. Introduction to semiconductors and semiconductor devices a background equalization lecture reading. Introduction formation of barrier current transport processes measurement of barrier height device structures ohmic contact. Device structure, equilibrium energy band diagram, electrostatic analysis, energy band diagram under bias, capacitancevoltage characteristics, image charge, dependence of barrier height on electric field, energy band diagram of schottky contact under bias, thermionic emission current, ohmic contact by heavy. Will be online after lecture 11 tuesday 19th february. Characterization of the metalsemiconductor interface of. Metalsemiconductor junction an overview sciencedirect topics. Metalsemiconductor interfaces rectifying schottky junction nonrectifying ohmic contacts 4.
At the same time, such contacts cannot be assumed to have a resistance as low as that of two connected metals. Metal semiconductor contacts are an obvious component of any semiconductor device. Metalsemiconductor interfaces rectifying schottky junction nonrectifying ohmic contacts 3. Metal semiconductor contact anchit biswas techno india,saltlake 2. Chapter 4 metalsemiconductor contacts and semiconductor. Topics covered include the factors that determine the height of the schottky barrier, its currentvoltage characteristics, and its capacitance. Figure 1 shows the energy band diagram after the contact is made. Metalsemiconductor contacts monographs in electrical and electronic engineering. Doitpoms tlp library introduction to semiconductors. The physics and technology of metalsemiconductor interfaces are keypoints in the development of silicon carbide sic based devices.
Purchase metal semiconductor contacts and devices, volume 1st edition. The metal oxide semiconductor field effect transistor mosfet is one of the cornerstones of modern semiconductor technology. Analytical model of the metalsemiconductor contact for. For a sufficiently large schottky barrier height, where. Parasuraman,department of metallurgy and material science,iit madras. Department of electronics engineering, national chiao tung university, hsinchu, taiwan. In this module on metal semiconductor contacts, we will cover the following topics. As the name implies, the ms junction is that a metal and a semiconductor material are contacted closely. May 16, 2018 the junctions formed at the contact between metallic electrodes and semiconductor materials are crucial components of electronic and optoelectronic devices 1. The metal semiconductor ms contact is an important component in the performance of most semiconductor devices in the solid state. Metalsemiconductor contacts fermi level pinning is the lack of barrier height modulation with metal work function due to either large density of intrinsic states. Several strategies, such as phase engineering to create lat eral metalsemiconductormetal heterojunctions 14, formation of. Semiconductor materials are a subclass of materials distinguished by the existence of a range of disallowed. Device structure, equilibrium energy band diagram, electrostatic analysis, energy band diagram under bias, capacitancevoltage characteristics, image charge, dependence of barrier height on electric field, energy band diagram of schottky contact under bias, thermionic emission current, ohmic.
Ohmic contact ms junction with large js v small linearize iv characteristics. Schottky barrier models 1 the schottkymott model according to schottky and mott 1938 the height of the barrier between a metal and an ntype semiconductor is given by q. Challenge of applying ohmic contacts to gallium arsenide. It is well known that the quality of metalsemiconductor contacts plays an important role in the performance of various semiconductor devices and integrated circuits. Written for semiconductor technologists and physicists. Importance of metal semiconductor contacts is due to l ohmic metal semiconductor junctions e. This section describes each of these contacts as well as an analysis of the contact resistance between a metal and a thin semiconductor layer. A metal semiconductor contacts without interface states. Electronic materials, devices, and fabrication by prof s. Metal semiconductor interfaces rectifying schottky junction nonrectifying ohmic contacts 4. Metal semiconductor interfaces rectifying schottky junction nonrectifying ohmic contacts 3.
Metaloxidesemiconductor mos fundamentals engineering. Metalsemiconductor contacts, leds, lasers, some solar cells, photodetectors. Metalsemiconductor contacts are an obvious component of any semiconductor device. For an ideal mosc structure, some properties should. Metalsemiconductor ohmic contacts rcsd r dp rext rov x y 0 sidewall gate silicide nextx novy year 1997 1999 2003 2006 2009 2012 min feature size 0. This second edition brings a greatly expanded treatment of the physics of schottkybarrier formation to its comprehensive discussion of modern semiconductor technology.
Ideal metal semiconductor contacts now lets bring the metal and semiconductor together e 0 m s metal semiconductor ntype s e c e fs e v e fm m. Topics covered include the currentvoltage relationship, the capacitance of rectifying contacts, and practical methods of fabricating contacts. A high doping narrows the depletion region and increases the probability for tunneling significantly. A short discussion is also given of practical contacts and their application in semiconductor technology, and a comparison is made with pn junctions. Importance of metal semiconductor contacts is due to 1 ohmic metal semiconductor junctions e. Characterization of the metalsemiconductor interface of gold.
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