Silicon-tin

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Silicon-tin
SiSn lattice viewed from 100 direction.svg

The view of the SiSn lattice as seen from the <100> direction. Silicon atoms further from the cross-section are displayed using a lighter shade of blue. The red atom is the Sn atom occupying a silicon lattice point.
Material typeAlloy

Silicon-tin or SiSn, is in general a term used for an alloy of the form Si(1-x)Snx. The molecular ratio of tin in silicon can vary based on the fabrication methods or doping conditions. In general, SiSn is known to be intrinsically semiconducting, [1] and even small amounts of Sn doping in silicon can also be used to create strain in the silicon lattice and alter the charge transport properties. [2]

Contents

Theoretical studies

Several theoretical works have shown SiSn to be semiconducting. [3] [4] These mainly include DFT-based studies. The band structures obtained using these works show a change in band gap of silicon with the inclusion of tin into the silicon lattice. Thus, like SiGe, SiSn has a variable band gap that can be controlled using Sn concentration as a variable. In 2015, Hussain et al. experimentally verified the tuning of band gap associated with the diffusion of tin using homogeneous, abrupt p-n junction diodes. [5]

Production

SiSn can be obtained experimentally using several approaches. For small quantity of Sn in silicon, the Czochralski process is well known. [6] [7] Diffusion of tin into silicon has also been tried extensively in the past. [8] [9] Sn has the same valency and electronegativity as silicon and can be found in the diamond cubic crystal structure (α-Sn). Thus, silicon and tin meet three out of the four Hume-Rothery rules for solid state solubility. The one criterion that is not met is that of difference in atomic size. The tin atom is substantially larger than the silicon atom (31.8%). This reduces the solid state solubility of tin in silicon. [10]

Electrical performance

The first MOSFET (metal–oxide–semiconductor field-effect transistor) using SiSn as a channel material was shown in 2013. [11] This study proved that SiSn can be used as semiconductor for MOSFET fabrication, and that there may be certain applications where the use of SiSn instead of silicon may be more advantageous. In particular, the off current of SiSn transistors is much lower than that of silicon transistors. [12] [13] Thus, logic circuits based on SiSn MOSFETs consume lower static power compared to silicon-based circuits. This is advantageous in battery operated devices (LSTP devices), where the standby power has to be reduced for longer battery life.

Thermal conductivity

Si-Sn alloys have the lowest conductivity (3   W/mK) of all the bulk alloys among Si-Ge, Ge-Sn, and Si-Ge-Sn; less than half that of Si-Ge which has been extensively studied, attributed to the larger difference in mass between the two constituents. [14] In addition, thin films offer an additional reduction in thermal conductivity, reaching around 1  W/mK in 20-nm-thick Si-Sn, Ge-Sn, and ternary Si-Ge-Sn films, which is near the conductivity of amorphous SiO2. [14] Group-IV alloys containing Sn have the potential for high-efficiency thermoelectric energy conversion. [14]

See also

Related Research Articles

A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. Its conducting properties may be altered in useful ways by introducing impurities ("doping") into the crystal structure. When two differently doped regions exist in the same crystal, a semiconductor junction is created. The behavior of charge carriers, which include electrons, ions, and electron holes, at these junctions is the basis of diodes, transistors, and most modern electronics. Some examples of semiconductors are silicon, germanium, gallium arsenide, and elements near the so-called "metalloid staircase" on the periodic table. After silicon, gallium arsenide is the second-most common semiconductor and is used in laser diodes, solar cells, microwave-frequency integrated circuits, and others. Silicon is a critical element for fabricating most electronic circuits.

<span class="mw-page-title-main">Transistor</span> Solid-state electrically operated switch also used as an amplifier

A transistor is a semiconductor device used to amplify or switch electrical signals and power. It is one of the basic building blocks of modern electronics. It is composed of semiconductor material, usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more in miniature form are found embedded in integrated circuits.

<span class="mw-page-title-main">Semiconductor device</span> Electronic component that exploits the electronic properties of semiconductor materials

A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material for its function. Its conductivity lies between conductors and insulators. Semiconductor devices have replaced vacuum tubes in most applications. They conduct electric current in the solid state, rather than as free electrons across a vacuum or as free electrons and ions through an ionized gas.

<span class="mw-page-title-main">MOSFET</span> Type of field-effect transistor

The metal-oxide-semiconductor field-effect transistor is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. A metal-insulator-semiconductor field-effect transistor (MISFET) is a term almost synonymous with MOSFET. Another synonym is IGFET for insulated-gate field-effect transistor.

A thin-film transistor (TFT) is a special type of field-effect transistor (FET) where the transistor is made by thin film deposition. TFTs are grown on a supporting substrate. A common substrate is glass, because the traditional application of TFTs is in liquid-crystal displays (LCDs). This differs from the conventional bulk metal oxide field effect transistor (MOSFET), where the semiconductor material typically is the substrate, such as a silicon wafer.

<span class="mw-page-title-main">Gallium nitride</span> Chemical compound

Gallium nitride is a binary III/V direct bandgap semiconductor commonly used in blue light-emitting diodes since the 1990s. The compound is a very hard material that has a Wurtzite crystal structure. Its wide band gap of 3.4 eV affords it special properties for applications in optoelectronic, high-power and high-frequency devices. For example, GaN is the substrate which makes violet (405 nm) laser diodes possible, without requiring nonlinear optical frequency-doubling.

<span class="mw-page-title-main">Thermoelectric materials</span> Materials whose temperature variance leads to voltage change

Thermoelectric materials show the thermoelectric effect in a strong or convenient form.

SiGe, or silicon–germanium, is an alloy with any molar ratio of silicon and germanium, i.e. with a molecular formula of the form Si1−xGex. It is commonly used as a semiconductor material in integrated circuits (ICs) for heterojunction bipolar transistors or as a strain-inducing layer for CMOS transistors. IBM introduced the technology into mainstream manufacturing in 1989. This relatively new technology offers opportunities in mixed-signal circuit and analog circuit IC design and manufacture. SiGe is also used as a thermoelectric material for high-temperature applications (>700 K).

<span class="mw-page-title-main">High-electron-mobility transistor</span> Type of field-effect transistor

A high-electron-mobility transistor, also known as heterostructure FET (HFET) or modulation-doped FET (MODFET), is a field-effect transistor incorporating a junction between two materials with different band gaps as the channel instead of a doped region. A commonly used material combination is GaAs with AlGaAs, though there is wide variation, dependent on the application of the device. Devices incorporating more indium generally show better high-frequency performance, while in recent years, gallium nitride HEMTs have attracted attention due to their high-power performance. Like other FETs, HEMTs are used in integrated circuits as digital on-off switches. FETs can also be used as amplifiers for large amounts of current using a small voltage as a control signal. Both of these uses are made possible by the FET’s unique current–voltage characteristics. HEMT transistors are able to operate at higher frequencies than ordinary transistors, up to millimeter wave frequencies, and are used in high-frequency products such as cell phones, satellite television receivers, voltage converters, and radar equipment. They are widely used in satellite receivers, in low power amplifiers and in the defense industry.

In semiconductor production, doping is the intentional introduction of impurities into an intrinsic semiconductor for the purpose of modulating its electrical, optical and structural properties. The doped material is referred to as an extrinsic semiconductor.

<span class="mw-page-title-main">Strained silicon</span>

Strained silicon is a layer of silicon in which the silicon atoms are stretched beyond their normal interatomic distance. This can be accomplished by putting the layer of silicon over a substrate of silicon–germanium. As the atoms in the silicon layer align with the atoms of the underlying silicon germanium layer, the links between the silicon atoms become stretched - thereby leading to strained silicon. Moving these silicon atoms farther apart reduces the atomic forces that interfere with the movement of electrons through the transistors and thus better mobility, resulting in better chip performance and lower energy consumption. These electrons can move 70% faster allowing strained silicon transistors to switch 35% faster.

Transistors are simple devices with complicated behavior. In order to ensure the reliable operation of circuits employing transistors, it is necessary to scientifically model the physical phenomena observed in their operation using transistor models. There exists a variety of different models that range in complexity and in purpose. Transistor models divide into two major groups: models for device design and models for circuit design.

<span class="mw-page-title-main">Hafnium(IV) oxide</span> Chemical compound

Hafnium(IV) oxide is the inorganic compound with the formula HfO
2. Also known as hafnium dioxide or hafnia, this colourless solid is one of the most common and stable compounds of hafnium. It is an electrical insulator with a band gap of 5.3~5.7 eV. Hafnium dioxide is an intermediate in some processes that give hafnium metal.

<span class="mw-page-title-main">Tin selenide</span> Chemical compound

Tin selenide, also known as stannous selenide, is an inorganic compound with the formula SnSe. Tin(II) selenide is a typical layered metal chalcogenide as it includes a group 16 anion (Se2−) and an electropositive element (Sn2+), and is arranged in a layered structure. Tin(II) selenide is a narrow band-gap (IV-VI) semiconductor structurally analogous to black phosphorus. It has received considerable interest for applications including low-cost photovoltaics, and memory-switching devices.

<span class="mw-page-title-main">Silicene</span> Two-dimensional allotrope of silicon

Silicene is a two-dimensional allotrope of silicon, with a hexagonal honeycomb structure similar to that of graphene. Contrary to graphene, silicene is not flat, but has a periodically buckled topology; the coupling between layers in silicene is much stronger than in multilayered graphene; and the oxidized form of silicene, 2D silica, has a very different chemical structure from graphene oxide.

<span class="mw-page-title-main">Field-effect transistor</span> Type of transistor

The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs are devices with three terminals: source, gate, and drain. FETs control the flow of current by the application of a voltage to the gate, which in turn alters the conductivity between the drain and source.

Lead tin telluride, also referred to as PbSnTe or Pb1−xSnxTe, is a ternary alloy of lead, tin and tellurium, generally made by alloying either tin into lead telluride or lead into tin telluride. It is a IV-VI narrow band gap semiconductor material.

Germanium-tin is an alloy of the elements germanium and tin, both located in group 14 of the periodic table. It is only thermodynamically stable under a small composition range. Despite this limitation, it has useful properties for band gap and strain engineering of silicon-integrated optoelectronic and microelectronic semiconductor devices.

Flexible silicon refers to a flexible piece of mono-crystalline silicon. Several processes have been demonstrated in the literature for obtaining flexible silicon from single crystal silicon wafers.

References

  1. ↑ Jensen, Rasmus V S; Pedersen, Thomas G; Larsen, Arne N (31 August 2011). "Quasiparticle electronic and optical properties of the Si–Sn system". Journal of Physics: Condensed Matter. 23 (34): 345501. Bibcode:2011JPCM...23H5501J. doi:10.1088/0953-8984/23/34/345501. PMID   21841232. S2CID   36811872.
  2. ↑ Simoen, E.; Claeys, C. (2000). "Tin Doping Effects in Silicon". Electrochem. Soc. Proc. 2000–17: 223.
  3. ↑ Amrane, Na.; Ait Abderrahmane, S.; Aourag, H. (August 1995). "Band structure calculation of GeSn and SiSn". Infrared Physics & Technology. 36 (5): 843–848. Bibcode:1995InPhT..36..843A. doi:10.1016/1350-4495(95)00019-U.
  4. ↑ Zaoui, A.; Ferhat, M.; Certier, M.; Khelifa, B.; Aourag, H. (June 1996). "Optical properties of SiSn and GeSn". Infrared Physics & Technology. 37 (4): 483–488. Bibcode:1996InPhT..37..483Z. doi:10.1016/1350-4495(95)00116-6.
  5. ↑ Hussain, Aftab M.; Wehbe, Nimer; Hussain, Muhammad M. (24 August 2015). "SiSn diodes: Theoretical analysis and experimental verification" (PDF). Applied Physics Letters. 107 (8): 082111. Bibcode:2015ApPhL.107h2111H. doi:10.1063/1.4929801. hdl: 10754/576462 .
  6. ↑ Claeys, C.; Simoen, E.; Neimash, V. B.; Kraitchinskii, A.; Kras’ko, M.; Puzenko, O.; Blondeel, A.; Clauws, P. (2001). "Tin Doping of Silicon for Controlling Oxygen Precipitation and Radiation Hardness". Journal of the Electrochemical Society. 148 (12): G738. Bibcode:2001JElS..148G.738C. doi:10.1149/1.1417558.
  7. ↑ Chroneos, A.; Londos, C. A.; Sgourou, E. N. (2011). "Effect of tin doping on oxygen- and carbon-related defects in Czochralski silicon" (PDF). Journal of Applied Physics. 110 (9): 093507–093507–8. Bibcode:2011JAP...110i3507C. doi:10.1063/1.3658261.
  8. ↑ Kringhøj, Per; Larsen, Arne (September 1997). "Anomalous diffusion of tin in silicon". Physical Review B. 56 (11): 6396–6399. Bibcode:1997PhRvB..56.6396K. doi:10.1103/PhysRevB.56.6396.
  9. ↑ Yeh, T. H. (1968). "Diffusion of Tin into Silicon". Journal of Applied Physics. 39 (9): 4266–4271. Bibcode:1968JAP....39.4266Y. doi:10.1063/1.1656959.
  10. ↑ Akasaka, Youichi; Horie, Kazuo; Nakamura, Genshiro; Tsukamoto, Katsuhiro; Yukimoto, Yoshinori (October 1974). "Study of Tin Diffusion into Silicon by Backscattering Analysis". Japanese Journal of Applied Physics. 13 (10): 1533–1540. Bibcode:1974JaJAP..13.1533A. doi:10.1143/JJAP.13.1533. S2CID   121383273.
  11. ↑ Hussain, Aftab M.; Fahad, Hossain M.; Singh, Nirpendra; Sevilla, Galo A. Torres; Schwingenschlögl, Udo; Hussain, Muhammad M. (2013). "Exploring SiSn as channel material for LSTP device applications". 71st Device Research Conference. pp. 93–94. doi:10.1109/DRC.2013.6633809. ISBN   978-1-4799-0814-1. S2CID   42075329.
  12. ↑ Hussain, Aftab M.; Fahad, Hossain M.; Singh, Nirpendra; Sevilla, Galo A. Torres; Schwingenschlögl, Udo; Hussain, Muhammad M. (13 January 2014). "Tin - an unlikely ally for silicon field effect transistors?". Physica Status Solidi RRL. 8 (4): 332–335. Bibcode:2014PSSRR...8..332H. doi:10.1002/pssr.201308300. S2CID   93729786.
  13. ↑ Hussain, Aftab M.; Fahad, Hossain M.; Singh, Nirpendra; Sevilla, Galo A. Torres; Schwingenschlögl, Udo; Hussain, Muhammad M. (2013). "Tin (Sn) for enhancing performance in silicon CMOS". 2013 IEEE 8th Nanotechnology Materials and Devices Conference (NMDC). pp. 13–15. doi:10.1109/NMDC.2013.6707470. ISBN   978-1-4799-3387-7. S2CID   21059449.
  14. 1 2 3 Khatami, S. N. (2016). "Lattice Thermal Conductivity of the Binary and Ternary Group-IV Alloys Si-Sn, Ge-Sn, and Si-Ge-Sn". Physical Review Applied. 6 (1): 014015. Bibcode:2016PhRvP...6a4015K. doi:10.1103/physrevapplied.6.014015.
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