Oxford science publications, 1988 2 atlas users manual, silvaco, 2007 3 s. The relations of section 3a after the substitutions na nd, imxsv i mxsc, en es es ed hold also for the mp contacts save 28 which, owing to the polarity of v see fig. Metal semiconductor contacts are an obvious component of any semiconductor device. Pdf barrier height enhancement of metalsemiconductor. Metal semiconductor interfaces rectifying schottky junction nonrectifying ohmic contacts 4. The term metal silicon contact includes silicidesi contacts.
Rhoderick, 9780198593362, available at book depository with free delivery worldwide. The problem with the metal semiconductor interface, and. Written for semiconductor technologists and physicists engaged this second edition brings a greatly expanded treatment of the physics of schottkybarrier formation to its comprehensive discussion of. Consider a metal semiconductor junction formed from a ptype semiconductor material and a metal such that. For example, good ohmic contacts are essential for achieving excellent performance of a semiconductor device, while schottky i.
Apr 20, 1978 topics covered include the currentvoltage relationship, the capacitance of rectifying contacts, and practical methods of fabricating contacts. The forward currentvoltage iv characteristics of au ngaas schottky barrier diodes sbds have been studied over a wide temperature range 80300 k. How do holes and electrons communicate with each other at the interface. Metal semiconductor interfaces rectifying schottky junction nonrectifying ohmic contacts 3. A mechanism of carriers transport through metal semiconductor interface created by nickel or titaniumbased ohmic contacts on siface ntype 4hsic is presented herein. Basic semiconductor material science and solidstate physics all terrestrial materials are made up of atoms. A 1 cm 3 specimen of a metal or semiconductor has of the order of 10 22 atoms. The doping profile is an important contributing factor to the currentvoltage relationship of a device. Problem 2 to calculate the effective richardson constant a from the iv characteristics. Basic semiconductor physics and technology 5 discussed at the end of section 3. For a sufficiently large schottky barrier height, where. Rhoderick, metalsemiconductor contacts, clarendon press, oxford 1978. The small barrier that exists for electron flow from metal to the semiconductor, but vanishes when.
Use features like bookmarks, note taking and highlighting while reading metal semiconductor contacts and devices issn. The barrier height inhomogeneities by assuming a gaussian distribution of barrier heights at the interface were observed. Metalsemiconductor contacts monographs in electrical and electronic engineering rhoderick, e. Metalsemiconductor contacts fermi level pinning is the lack of barrier height modulation with metal work function due to either large density of intrinsic states. 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. Experimental studies of metals on semiconductors 3. Challenge of applying ohmic contacts to gallium arsenide. Rhoderick, 1988, clarendon press, oxford university press edition, in english 2nd ed. The ohmic barrier is thin enough to permit tunneling. Ohmic metal contact to ptype semiconductors with a large bandgap, like filename. Consider a contact between tungsten and ntype silicon doped to nd1016cm3 at t 300k. Lecture 17 metalsemiconductor junction march 14, 2007 contents. Microstructure, electrical properties, and thermal stability. This is a rectifying junction, since holes are the majority carriers in the p.
By having proper doping profiles and having a smooth interfacial contact layer. S do not change when the metal and the semiconductor are. Schematic band diagrams at metalsemiconductor contacts without interface states. In many cases, we wish to have a perfect ohmic metal.
It is well known that the quality of metalsemiconductor. 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. Metalsemiconductor contacts monographs in electrical and. Whether a given metalsemiconductor junction is an ohmic contact or a schottky barrier depends on the schottky barrier height. Semiconductor physics and technology free pdf file sharing. Metal semiconductor 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. Mechanisms of carriers transport in ninsic, tinsic ohmic. 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. Providing selfalignment for metallization, we avoid the limitations to tight integration found in previously reported methods. In particular, a large mismatch between the fermi energy of the metal and semiconductor can result is a highresistance rectifying contact. Characterization of metalsemiconductor contacts using. Doitpoms tlp library introduction to semiconductors metal. Low resistance ohmic contacts are used to allow charge to flow easily in both directions between the two conductors, without blocking due to rectification or excess power dissipation due to voltage thresholds.
Schottky contacts using conducting probe atomic force microscopy cafm. Williams, metal semiconductor contacts, 2nd edition, clarendon press, oxford, 1988. Metalsemiconductor contacts schottky contacts metal on lightly doped silicon rectifying ohmic contacts metal on heavily doped silicon low resistance 2 november. Rhoderick is professor of solidstate electronics, department of.
However, it was not until the twentieth century that the atomic theory of matter became firmly established as an unassailable, demonstrated fact. 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. 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. Ideal metalsemiconductor junction outside equilib rium reading assignment. The properties of these contacts can vary considerably depending on the nature of the interface with the semiconductor. Metalsemiconductor contacts display a range of electrical characteristics from strongly rectifying to ohmic, each having its own applications. A fundamental study of advanced metalsemiconductor contacts.
Yangc a school of electrical and computer engineering and birck nanotechnology center, purdue university, west lafayette, in 47907, usa b asm america, 3440 east university drive, phoenix, az. B is significantly higher than the thermal energy kt, the semiconductor is depleted near the metal and behaves as a schottky barrier. In solidstate physics, a metal semiconductor ms junction is a type of electrical junction in which a metal comes in close contact with a semiconductor material. Metal semiconductor contacts and devices issn kindle edition by cohen, simon s. An alternate and more practical contact is a tunnel contact. It is well known that the quality of metalsemiconductor contacts plays an important role in the performance of various semiconductor devices and integrated circuits. Metal semi conductor junction need for metal sc junction as metal contacts to connect external circuitry with the device semiconductor device junction formation bw metal contact and sc effect of metal sc junction variation in device behavior control may lost v 5. Lecture 17 metal semiconductor junction march 14, 2007 contents. Gan metalsemiconductormetal ultraviolet photodetector with iro2 schottky contact article pdf available in applied physics letters 8124. At the same time, such contacts cannot be assumed to have a resistance as low as that of two connected metals. The presentday semiconductor technology would be inconceivable without extensive use of schottky barrier junctions. Metalsemiconductor interfaces investigated by positron.
Barrier height enhancement of metalsemiconductor contact. The role of interface state density in iv characteristics. Ms junctions can either be rectifying or nonrectifying. Barrier height enhancement of metalsemiconductor contact by an enzyme biofilm interlayer article pdf available in philosophical magazine 9317. This second edition brings a greatly expanded treatment of the physics of schottkybarrier formation to its comprehensive discussion of modern. Materials science and engineering b 5 2006 282284 gan metal oxide semiconductor. The rectifying properties of metal points on metallic sulphides were used extensively as detectors in early radio experiments, while during the second world war the rectifying point contact diode became important as a frequency detector and low level. 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. Currentvoltagetemperature analysis of inhomogeneous aun. Metal semiconductor contacts rhoderick pdf 15 phivelme. A schottky barrier is similar to a pn junction or heterojunction in which the doping on one side increases to the point where it becomes metallic. A mechanism of carriers transport through metalsemiconductor interface created by nickel or titaniumbased ohmic contacts on siface ntype 4hsic is presented herein. Electrical characterization and modelling of schottky barrier metal sourcedrain mosfets.
The method yields a pristine surface for making metal semiconductor contacts. Topics covered include the currentvoltage relationship, the capacitance of rectifying contacts, and practical methods of fabricating contacts. Metalsemiconductor schottky barrier junctions and their. Metal semiconductor contact with interfacial layer saroj bala assistant professor, dav college, sector 10, chandigarh india abstract the metal insulator semiconductor mis diode is the most useful device in the study of semiconductor surfaces. Metal semiconductor contact anchit biswas techno india,saltlake 2. Nov 02, 2015 metalsemiconductor contacts kasif nabi imi2015007 department of microelectronics indian institute of information technology allahabad 2nd november 2 november 2015 1 2. Lowresistance metal semiconductor contacts using degenerate surface layers. Mechanisms of carriers transport in ninsic, tinsic. Metalsemiconductor contacts 1988 edition open library. Microstructure, electrical properties, and thermal. Written for semiconductor technologists and physicists engaged in research on semiconductor interfaces, this text emphasizes practical implications wherever they are relevant to device technology. Metalsemiconductor contacts monographs in electrical and electronic engineering. The study of metalsemiconductor contacts goes back to 1874, when braun.
Topics covered include the factors that determine the height of the schottky barrier. The mechanism was observed within the temperature range of 20 c. An ohmic contact is a nonrectifying electrical junction. Semiconductor rectifying contacts semantic scholar. Schematic band diagrams at metal semiconductor contacts without interface states. The effect of interface states on the barrier heights of metalsemiconductor contacts was first analyzed by cowley and sze 33. The rectifying metal semiconductor junction forms a schottky barrier, making a device known as a schottky diode, while. Unlimited viewing of the articlechapter pdf and any associated supplements and figures. Since the workfunction of most metals is less than 5 v and a typical electron affinity is about 4 v, it can be problematic to find a metal that provides an ohmic contact to ptype semiconductors with a large bandgap such as gan or sic. Indeed, the ancient greeks put this hypothesis forward over two millennia ago. The method eliminates the need for precision lithography for highly accurate alignment of the via. Microstructure, electrical properties, and thermal stability of tibased ohmic contacts to ngan volume 14 issue 3 l. The metal oxide semiconductor field effect transistor mosfet is one of the cornerstones of modern semiconductor technology.
The term metalsilicon contact includes silicidesi contacts. Department of electronics engineering, national chiao tung university, hsinchu, taiwan. It is well known that the quality of metalsemiconductor contacts plays an. Importance of metal semiconductor contacts is due to l ohmic metal semiconductor junctions e. The band diagram of an ideal metal on ntype semiconductor schottky barrier is shown in figs. The effect of interface states on the barrier heights of metal semiconductor contacts was first analyzed by cowley and sze 33. 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. Metalsemiconductor ohmic contacts stanford university. 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. Current begins to flow from the semiconductor to the metal. A detailed analysis of the metalsemiconductor contact. They can behave either as a schottky barrier or as an ohmic contact dependent on the characteristics of the interface. Metal to semiconductor ms junctions are of great importance since they are present in every semiconductor device. Schottky barrier parameters of pdti contacts on ntype inp revealed from ivt and cvt measurements.