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Vertical InAs Nanowire Devices and RF Circuits

Berg, Martin LU (2015) In Series of licentiate and doctoral theses 73.
Abstract (Swedish)
Popular Abstract in Swedish

Under de senaste årtiondena har prestandan i elektriska kretsar växt i en rasande takt. Detta har lett till otaliga innovationer som har förbättrat samhället. Grunden till denna utveckling grundar sig i två uppfinningar: transistorn och den integrerade kresten.



Till skillnad från många andra grundläggande elektroniska komponenter har en transistor tre elektroder. En elektrisk ström skickas mellan två av elektroderna, såsom i ett motstånd, medans den tredje elektroden används för att styra hur stor denna ström ska vara. Det är detta styre, även kallad gate, som gör det möjligt att använda transistorn till digitala beräkningar, som är grunden i datorer, och till analoga... (More)
Popular Abstract in Swedish

Under de senaste årtiondena har prestandan i elektriska kretsar växt i en rasande takt. Detta har lett till otaliga innovationer som har förbättrat samhället. Grunden till denna utveckling grundar sig i två uppfinningar: transistorn och den integrerade kresten.



Till skillnad från många andra grundläggande elektroniska komponenter har en transistor tre elektroder. En elektrisk ström skickas mellan två av elektroderna, såsom i ett motstånd, medans den tredje elektroden används för att styra hur stor denna ström ska vara. Det är detta styre, även kallad gate, som gör det möjligt att använda transistorn till digitala beräkningar, som är grunden i datorer, och till analoga applikationer, såsom radiosändare och mottagare. I en integrerad krets tillverkas idag miljardtals transistorer sida vid sida i halvledarmaterialet kisel. Att tillverka transistorerna på detta sätt är väldigt kostnadseffektivt och gör det möjligt att tillverka stora kretsar, såsom processorer. Under åren har tillverkningsmetoderna av integrerade kretsar utvecklats och lett till en förminskning av transistorernas storlek. De minsta dimensionerna i en modern transistor motsvarar idag ett par tiotal atomer i bredd. Ytterligare miniatyrisering är komplicerad och detta har lett till mycket forskning kring alternativa material och transistorstrukturer.



I detta arbete studeras användandet av halvledande nanotrådar i transistorer. Nanotrådar är cylindriska pelare i nanometerskalan. Genom att linda styret kring den nanotråden kan styrningen av strömmen göras effektivare än i konventionella transistorer. Nanotrådar kan byggas av flera halvledarmaterial, där indiumarsenid är ett av de materialen som har högst rörlighet för elektroner. Genom att kombinera materialegenskaperna av indiumarsenid med fördelarna av att nyttja en nanotråd, har välfungerande transistorer tillverkats. Under arbetets gång har InAs-transistorerna flyttats till kisel för att visa på ett kostnadseffektivt sätt att tillverka högprestandatransistorer. (Less)
Abstract
Recent decades have seen an exponential increase in the functionality of electronic circuits, allowing for continuous innovation, which benefits society. This increase in functionality has been facilitated by scaling down the dimensions of the most important electronic component in modern electronics: the Si-based MOSFET. By reducing the size of the device, more transistors per chip area is possible. Smaller MOSFETs are also faster and more energy-efficient. In state of the art MOSFETs, the key dimensions are only few nanometers, rapidly approaching a point where the current scaling scheme may not be maintained. Research is ongoing to improve the device performance, mainly focusing on material and structural improvements to the existing... (More)
Recent decades have seen an exponential increase in the functionality of electronic circuits, allowing for continuous innovation, which benefits society. This increase in functionality has been facilitated by scaling down the dimensions of the most important electronic component in modern electronics: the Si-based MOSFET. By reducing the size of the device, more transistors per chip area is possible. Smaller MOSFETs are also faster and more energy-efficient. In state of the art MOSFETs, the key dimensions are only few nanometers, rapidly approaching a point where the current scaling scheme may not be maintained. Research is ongoing to improve the device performance, mainly focusing on material and structural improvements to the existing MOSFET architecture.



In this thesis, MOSFETs based on nanowires, are investigated. Taking advantage of the nanowire geometry, the gate can be wrapped all-around the nanowires for excellent control of the channel. The nanowires are made in a high-mobility III-V semiconductor, InAs, allowing for faster electrons and higher currents than Si. This device type is a potential candidate to either replace or complement Si-based MOSFETs in digital and analogue applications. Single balanced down-conversion mixer circuits were fabricated, consisting of three vertically aligned InAs nanowire MOSFETs and two nanowire resistors. These circuits are shown to operate with voltage gain in the GHz-regime. Individual transistors demonstrated operation with gain at several tens of GHz.



A method to characterise the resistivity and metal-semiconductor contact quality has been developed, using the transmission line method adapted for vertical nanowires. This method has successfully been applied to InAs nanowires and shown that low-resistance contacts to these nanowires are possible. To optimise the performance of the device and reach as close to intrinsic operation as possible, parasitic capacitances and resistances in the device structure need to be minimised. A novel self-aligned gate-last fabrication method for vertical InAs nanowire transistors has been developed, that allows for an optimum design of the channel and the contact regions. Transistors fabricated using this method exhibit the best DC performance, in terms of a compromise between the normalised transconductance and sub-threshold swing, of any previously reported vertical nanowire MOSFET. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Dr. Weber, Walter, NaMLab, Dresden, Germany
organization
publishing date
type
Thesis
publication status
published
subject
keywords
MOSFET, Metal-oxide-semiconductor field-effect transistor, Transistor, Vertical, InAs, III-V semiconductor, Nanowire, Fabrication, DC, Resistor, TLM, RF, Mixer, Circuit.
in
Series of licentiate and doctoral theses
volume
73
pages
160 pages
publisher
Lund University
defense location
Lecture hall E:1406, E-building, Ole Römers väg 3, Lund University Faculty of Engineering
defense date
2015-09-29 10:15
ISSN
1654-790X
ISBN
978-91-7623-382-5
project
EIT_WWW Wireless with Wires
language
English
LU publication?
yes
id
f97f26a5-e5a3-4fd2-b774-6e75dc56edb8 (old id 7852217)
date added to LUP
2015-09-07 10:28:25
date last changed
2016-09-19 08:44:45
@phdthesis{f97f26a5-e5a3-4fd2-b774-6e75dc56edb8,
  abstract     = {Recent decades have seen an exponential increase in the functionality of electronic circuits, allowing for continuous innovation, which benefits society. This increase in functionality has been facilitated by scaling down the dimensions of the most important electronic component in modern electronics: the Si-based MOSFET. By reducing the size of the device, more transistors per chip area is possible. Smaller MOSFETs are also faster and more energy-efficient. In state of the art MOSFETs, the key dimensions are only few nanometers, rapidly approaching a point where the current scaling scheme may not be maintained. Research is ongoing to improve the device performance, mainly focusing on material and structural improvements to the existing MOSFET architecture. 	<br/><br>
<br/><br>
In this thesis, MOSFETs based on nanowires, are investigated. Taking advantage of the nanowire geometry, the gate can be wrapped all-around the nanowires for excellent control of the channel. The nanowires are made in a high-mobility III-V semiconductor, InAs, allowing for faster electrons and higher currents than Si. This device type is a potential candidate to either replace or complement Si-based MOSFETs in digital and analogue applications. Single balanced down-conversion mixer circuits were fabricated, consisting of three vertically aligned InAs nanowire MOSFETs and two nanowire resistors. These circuits are shown to operate with voltage gain in the GHz-regime. Individual transistors demonstrated operation with gain at several tens of GHz.	<br/><br>
<br/><br>
A method to characterise the resistivity and metal-semiconductor contact quality has been developed, using the transmission line method adapted for vertical nanowires. This method has successfully been applied to InAs nanowires and shown that low-resistance contacts to these nanowires are possible. To optimise the performance of the device and reach as close to intrinsic operation as possible, parasitic capacitances and resistances in the device structure need to be minimised. A novel self-aligned gate-last fabrication method for vertical InAs nanowire transistors has been developed, that allows for an optimum design of the channel and the contact regions. Transistors fabricated using this method exhibit the best DC performance, in terms of a compromise between the normalised transconductance and sub-threshold swing, of any previously reported vertical nanowire MOSFET.},
  author       = {Berg, Martin},
  isbn         = {978-91-7623-382-5},
  issn         = {1654-790X},
  keyword      = {MOSFET,Metal-oxide-semiconductor field-effect transistor,Transistor,Vertical,InAs,III-V semiconductor,Nanowire,Fabrication,DC,Resistor,TLM,RF,Mixer,Circuit.},
  language     = {eng},
  pages        = {160},
  publisher    = {Lund University},
  school       = {Lund University},
  series       = {Series of licentiate and doctoral theses},
  title        = {Vertical InAs Nanowire Devices and RF Circuits},
  volume       = {73},
  year         = {2015},
}