| 41. |
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| 42. |
- Jönsson, Adam, et al.
(författare)
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Doping Profiles in Ultrathin Vertical VLS-Grown InAs Nanowire MOSFETs with High Performance
- 2021
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Ingår i: ACS Applied Electronic Materials. - : American Chemical Society (ACS). - 2637-6113. ; 3:12, s. 5240-5247
-
Tidskriftsartikel (refereegranskat)abstract
- Thin vertical nanowires based on III-V compound semiconductors are viable candidates as channel material in metal oxide semiconductor field effect transistors (MOSFETs) due to attractive carrier transport properties. However, for improved performance in terms of current density as well as contact resistance, adequate characterization techniques for resolving doping distribution within thin vertical nanowires are required. We present a novel method of axially probing the doping profile by systematically changing the gate position, at a constant gate length Lg of 50 nm and a channel diameter of 12 nm, along a vertical nanowire MOSFET and utilizing the variations in threshold voltage VT shift (∼100 mV). The method is further validated using the well-established technique of electron holography to verify the presence of the doping profile. Combined, device and material characterizations allow us to in-depth study the origin of the threshold voltage variability typically present for metal organic chemical vapor deposition (MOCVD)-grown III-V nanowire devices.
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| 43. |
- Jönsson, Adam, et al.
(författare)
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Gate-Length Dependence of Vertical GaSb Nanowire p-MOSFETs on Si
- 2020
-
Ingår i: IEEE Transactions on Electron Devices. - 0018-9383. ; 67:10, s. 4118-4122
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of gate-length variation on key transistor metrics for vertical nanowire p-type GaSb metal-oxide-semiconductor field-effect transistors (MOSFETs) are demonstrated using a gate-last process. The new fabrication method enables short gate-lengths (Lg = 40 nm) and allows for selective digital etching of the channel region. Extraction of material properties as well as contact resistance are obtained by systematically varying the gate-length. The fabricated transistors show excellent modulation properties with a maximum Ion/Ioff = 700 (VGS = -0.5,,V) as well as peak transconductance of 50 μS/μm with a linear subthreshold swing of 224 mV/dec.
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| 44. |
- Karlsson, Sofia, 1982, et al.
(författare)
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A Laboratory Study of the in Situ Sulfation of Alkali Chloride Rich Deposits: Corrosion Perspective
- 2016
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 30:9, s. 7256-7267
-
Tidskriftsartikel (refereegranskat)abstract
- The initial corrosive effect of small (1.35 mu mol/cm(2)) and large (13.5 mu mol/cm(2)) amounts of KCl on 304L has been investigated. The investigations were performed in both the absence and presence of 300 ppm of SO2 at 600 degrees C. The results showed that in the absence of SO2 KCl accelerates the rate of corrosion by means of two types of corrosion attack: a general attack and a steel grain boundary attack. The general attack has been proved to be initiated by K2CrO4 formation. Meanwhile, the steel grain boundary attack is suggested to be accelerated by HCl released due to the chromate formation which increased with higher amounts of KCl. The presence of KCl and SO2 resulted in the simultaneous formation of K2SO4 and K2CrO4. The chromate formation resulted in a general corrosion attack. However, the oxide growth was significantly reduced due to the very fast sulfation reaction. In contrast, the steel grain boundary attack increased in the presence of SO2. It is suggested that the attack is accelerated by HCl released from the sulfation reaction and by sulfidation of the steel grain boundaries.
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| 45. |
- Kilpi, Olli Pekka, et al.
(författare)
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Electrical Properties of Vertical InAs/InGaAs Heterostructure MOSFETs
- 2019
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Ingår i: IEEE Journal of the Electron Devices Society. - 2168-6734. ; 7, s. 70-75
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Tidskriftsartikel (refereegranskat)abstract
- Vertical InAs/InGaAs nanowire MOSFETs are fabricated in a gate-last fabrication process, which allows gate-lengths down to 25 nm and accurate gate-alignment. These devices demonstrate high performance with transconductance of 2.4 mS/μm, high on-current, and off-current below 1 nA/μm. An in-depth analysis of the heterostructure MOSFETs are obtained by systematically varying the gate-length and gate location. Further analysis is done by using virtual source modeling. The injection velocities and transistor metrics are correlated with a quasi-ballistic 1-D MOSFET model. Based on our analysis, the observed performance improvements are related to the optimized gate-length, high injection velocity due to asymmetric scattering, and low access resistance.
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| 46. |
- Kilpi, Olli Pekka, et al.
(författare)
-
High-Performance Vertical III-V Nanowire MOSFETs on Si with gm> 3 mS/μm
- 2020
-
Ingår i: IEEE Electron Device Letters. - 0741-3106. ; 41:8, s. 1161-1164
-
Tidskriftsartikel (refereegranskat)abstract
- Vertical III-V nanowire MOSFETs have demonstrated excellent performance including high transconductance and high Ion. One main bottleneck for the vertical MOSFETs is the large access resistance arising from the contacts and ungated regions. We demonstrate a process to reduce the access resistance by combining a gate-last process with ALD gate-metal deposition. The devices demonstrate fully scalable gm down to Lg = 25 nm. These vertical core/shell InAs/InGaAs MOSFETs demonstrate gm = 3.1 mS/μm and Ron = 190 Ωμm. This is the highest gm demonstrated on Si. Transmission line measurement verifies a low contact resistance with RC = 115 Ωμm, demonstrating that most of the MOSFET access resistance is located in the contact regions.
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| 47. |
- Kilpi, Olli Pekka, et al.
(författare)
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Increased Breakdown Voltage in Vertical Heterostructure III-V Nanowire MOSFETs with a Field Plate
- 2021
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Ingår i: IEEE Electron Device Letters. - 0741-3106. ; 42:11, s. 1596-1598
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Tidskriftsartikel (refereegranskat)abstract
- Vertical III-V heterostructure MOSFETs exhibit outstanding performance at reduced supply voltages. In this paper, we report on a novel process of extending high-speed device operation towards higher voltages. The device vertical geometry allows for engineering a field plate by covering the nanowire drain area with a 10-nm-thick SiO2 film. The film acts as a field moderator in the device drain region. Reference devices without a field plate exhibit a transconductance of 2.5 mS/μm, while devices with a 120-nm-long field plate show 1.5 mS/μm but a three times increase in breakdown voltage. Measurements show that the field-screening effect attributes to reduced band-to-band tunneling and impact ionization, thereby reducing the parasitic bipolar effect in the MOSFET channel as well. The devices show promise in applications in circuits and systems requiring large power-handling.
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| 48. |
- Kilpi, Olli Pekka, et al.
(författare)
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Vertical heterojunction InAs/InGaAs nanowire MOSFETs on Si with Ion = 330 μa/μm at Ioff = 100 nA/μm and VD = 0.5 v
- 2017
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Ingår i: 2017 Symposium on VLSI Technology, VLSI Technology 2017. - 9784863486058 ; , s. 36-37
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Konferensbidrag (refereegranskat)abstract
- We present vertical InAs nanowire MOSFETs on Si with an In0.7Ga0.3As drain. The devices show Ion and gm/SS record performance for vertical MOSFETs and Ioff below 1 nA/μm at Vd 0.5 V. We show a device with gm=1.4 mS/μm and SS=85 mV/dec, therefore having Q-value (gm/SS) of 16. The device has Ion=330 μA/μm and 46 μA/μm at Ioff 100 nA/μm and 1 nA/μm, respectively. Furthermore, we show a device with SS=68 mV/dec and Ion=88 μA/μm at Ioff 1 nA/μm and Vd 0.5 V.
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| 49. |
- Kilpi, Olli Pekka, et al.
(författare)
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Vertical InAs/InGaAs Heterostructure Metal-Oxide-Semiconductor Field-Effect Transistors on Si
- 2017
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 17:10, s. 6006-6010
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Tidskriftsartikel (refereegranskat)abstract
- III-V compound semiconductors offer a path to continue Moore's law due to their excellent electron transport properties. One major challenge, integrating III-V's on Si, can be addressed by using vapor-liquid-solid grown vertical nanowires. InAs is an attractive material due to its superior mobility, although InAs metal-oxide-semiconductor field-effect transistors (MOSFETs) typically suffer from band-to-band tunneling caused by its narrow band gap, which increases the off-current and therefore the power consumption. In this work, we present vertical heterostructure InAs/InGaAs nanowire MOSFETs with low off-currents provided by the wider band gap material on the drain side suppressing band-to-band tunneling. We demonstrate vertical III-V MOSFETs achieving off-current below 1 nA/μm while still maintaining on-performance comparable to InAs MOSFETs; therefore, this approach opens a path to address not only high-performance applications but also Internet-of-Things applications that require low off-state current levels.
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| 50. |
- Kilpi, Olli-Pekka, et al.
(författare)
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Vertical nanowire III–V MOSFETs with improved high-frequency gain
- 2020
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 56:13, s. 669-671
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Tidskriftsartikel (refereegranskat)abstract
- High-frequency performance of vertical InAs/InGaAs heterostructure nanowire MOSFETs on Si is demonstrated for the first time for a gate-last configuration. The device architecture allows highly asymmetric capacitances, which increases the power gain. A device with Lg = 120 nm demonstrates fT = 120 GHz, fmax = 130 GHz and maximum stable gain (MSG) = 14.4 dB at 20 GHz. These metrics demonstrate the state-of-the-art performance of vertical nanowire MOSFETs.
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