Vertical III-V Nanowire MOSFETs
(2019) In Series of licentiate and doctoral theses- Abstract
- Vertical III-V nanowire MOSFETs are interesting candidates for future digital and analog applications. High electron velocity III-V materials allow fabrication of low power and high frequency MOSFETs. Vertical vapor-liquid-solid growth enables fabrication of axial and radial heterostructure nanowires. This enables fabrication of novel structures where the band-gap can be engineered in the electron transport direction.
In this thesis, vertical InAs/InGaAs DC and RF MOSFETs on Si are fabricated and characterized. Several novel structures in vertical nanowire MOSFETs have been implemented such as gate-last process, axial/radial heterostructures, sub-30-nm gate-length, optimized RF design and field-plate structures. Several different... (More) - Vertical III-V nanowire MOSFETs are interesting candidates for future digital and analog applications. High electron velocity III-V materials allow fabrication of low power and high frequency MOSFETs. Vertical vapor-liquid-solid growth enables fabrication of axial and radial heterostructure nanowires. This enables fabrication of novel structures where the band-gap can be engineered in the electron transport direction.
In this thesis, vertical InAs/InGaAs DC and RF MOSFETs on Si are fabricated and characterized. Several novel structures in vertical nanowire MOSFETs have been implemented such as gate-last process, axial/radial heterostructures, sub-30-nm gate-length, optimized RF design and field-plate structures. Several different nanowire compositions, such as InAs, InAs/In0.7Ga0.3As and InAs/In0.4Ga0.6As, were used. The radial heterostructureand the gate-last process enabled a record low access resistance in these devices. The axial heterostructure, on the other hand, allowed a wider band-gap material on the drain side, therefore suppressing the band-to-band tunnelling and impact ionization. This enabled a considerable improvement in the transistor off-state performance and for the first time Ioff < 1 nA/µm was reported in non-planar In(Ga)As MOSFETs.
This work demonstrated several high performance devices, therefore highlighting the potential of the vertical nanowire MOSFETs. We demonstrate Ion = 407 mA/µm at Ioff = 100 nA/µm and VDD = 0.5 V, which is the highest reported Ion on vertical nanowire MOSFETs. We demonstrated gm = 3.1 mS/µm, which is the highest demonstrated gm on any MOSFET on Si. Further, we increased the breakdown voltage on InAs/InGaAs MOSFETs from 0.5 V to 2.5 V and demonstrated vertical nanowire MOSFETs with fT/ fmax > 100 GHz / 100 GHz. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/00415d54-4258-4913-9a3f-2a8efadd13fe
- author
- Kilpi, Olli-Pekka LU
- supervisor
- opponent
-
- Professor Takagi, Shinichi, The University of Tokyo, Japan
- organization
- publishing date
- 2019
- type
- Thesis
- publication status
- published
- subject
- keywords
- Nanowire, MOSFET, III-V, InGaAs, Vertical, Heterostructure, High frequency
- in
- Series of licentiate and doctoral theses
- issue
- 125
- pages
- 90 pages
- publisher
- Department of Electrical and Information Technology, Lund University
- defense location
- Lecture Hall E:1406, E-Building, Ole Römers väg 3, Lund University, Faculty of Engineering LTH
- defense date
- 2019-10-11 09:15:00
- ISSN
- 1654-790X
- ISBN
- 978-91-7895-293-9
- 978-91-7895-292-2
- language
- English
- LU publication?
- yes
- id
- 00415d54-4258-4913-9a3f-2a8efadd13fe
- date added to LUP
- 2019-09-17 13:37:16
- date last changed
- 2021-04-15 10:13:22
@phdthesis{00415d54-4258-4913-9a3f-2a8efadd13fe, abstract = {{Vertical III-V nanowire MOSFETs are interesting candidates for future digital and analog applications. High electron velocity III-V materials allow fabrication of low power and high frequency MOSFETs. Vertical vapor-liquid-solid growth enables fabrication of axial and radial heterostructure nanowires. This enables fabrication of novel structures where the band-gap can be engineered in the electron transport direction.<br/><br/>In this thesis, vertical InAs/InGaAs DC and RF MOSFETs on Si are fabricated and characterized. Several novel structures in vertical nanowire MOSFETs have been implemented such as gate-last process, axial/radial heterostructures, sub-30-nm gate-length, optimized RF design and field-plate structures. Several different nanowire compositions, such as InAs, InAs/In<sub>0.7</sub>Ga<sub>0.3</sub>As and InAs/In<sub>0.4</sub>Ga<sub>0.6</sub>As, were used. The radial heterostructureand the gate-last process enabled a record low access resistance in these devices. The axial heterostructure, on the other hand, allowed a wider band-gap material on the drain side, therefore suppressing the band-to-band tunnelling and impact ionization. This enabled a considerable improvement in the transistor off-state performance and for the first time I<sub>off</sub> < 1 nA/µm was reported in non-planar In(Ga)As MOSFETs.<br/><br/>This work demonstrated several high performance devices, therefore highlighting the potential of the vertical nanowire MOSFETs. We demonstrate I<sub>on</sub> = 407 mA/µm at I<sub>off </sub>= 100 nA/µm and V<sub>DD</sub> = 0.5 V, which is the highest reported I<sub>on</sub> on vertical nanowire MOSFETs. We demonstrated g<sub>m</sub> = 3.1 mS/µm, which is the highest demonstrated g<sub>m</sub> on any MOSFET on Si. Further, we increased the breakdown voltage on InAs/InGaAs MOSFETs from 0.5 V to 2.5 V and demonstrated vertical nanowire MOSFETs with fT/ fmax > 100 GHz / 100 GHz.}}, author = {{Kilpi, Olli-Pekka}}, isbn = {{978-91-7895-293-9}}, issn = {{1654-790X}}, keywords = {{Nanowire; MOSFET; III-V; InGaAs; Vertical; Heterostructure; High frequency}}, language = {{eng}}, number = {{125}}, publisher = {{Department of Electrical and Information Technology, Lund University}}, school = {{Lund University}}, series = {{Series of licentiate and doctoral theses}}, title = {{Vertical III-V Nanowire MOSFETs}}, year = {{2019}}, }