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Electrostatic Engineering using Extreme Permittivity Materials for Ultra-wide Bandgap Semiconductor Transistors
Authors:
Nidhin Kurian Kalarickal,
Zixuan Feng,
A F M Anhar Uddin Bhuiyan,
Zhanbo Xia,
Joe F. McGlone,
Wyatt Moore,
Aaron R. Arehart,
Steven A. Ringel,
Hongping Zhao,
Siddharth Rajan
Abstract:
The performance of ultra-wide band gap materials like $β$-Ga$_\mathrm{2}$O$_\mathrm{3}$ is critically dependent on achieving high average electric fields within the active region of the device. In this report, we show that high-k gate dielectrics like BaTiO$_\mathrm{3}$ can provide an efficient field management strategy by improving the uniformity of electric field profile in the gate-drain region…
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The performance of ultra-wide band gap materials like $β$-Ga$_\mathrm{2}$O$_\mathrm{3}$ is critically dependent on achieving high average electric fields within the active region of the device. In this report, we show that high-k gate dielectrics like BaTiO$_\mathrm{3}$ can provide an efficient field management strategy by improving the uniformity of electric field profile in the gate-drain region of lateral field effect transistors. Using this strategy, we were able to achieve high average breakdown fields of 1.5 MV/cm and 4 MV/cm at gate-drain spacing (L$_\mathrm{gd}$) of 6 um and 0.6 um respectively in $β$-Ga$_\mathrm{2}$O$_\mathrm{3}$, at a high channel sheet charge density of 1.8x10$^\mathrm{13}$cm$^\mathrm{-2}$. The high sheet charge density together with high breakdown field enabled a record power figure of merit (V$^\mathrm{2}$$_\mathrm{br}$/R$_\mathrm{on}$) of 376 MW/cm$^\mathrm{2}$ at a gate-drain spacing of 3 um.
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Submitted 3 June, 2020;
originally announced June 2020.
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Probing charge transport and background doping in MOCVD grown (010) $β$-Ga$_{2}$O$_{3}$
Authors:
Zixuan Feng,
A F M Anhar Uddin Bhuiyan,
Zhanbo Xia,
Wyatt Moore,
Zhaoying Chen,
Joe F. McGlone,
David R. Daughton,
Aaron R. Arehart,
Steven A. Ringel,
Siddharth Rajan,
Hongping Zhao
Abstract:
A new record-high room temperature electron Hall mobility ($μ_{RT} = 194\space cm^{2}/V\space s$ at $n\sim 8\times 10^{15}\space cm^{-3}$) for $β$-Ga2O3 is demonstrated in the unintentionally doped thin film grown on (010) semi-insulating substrate via metalorganic chemical vapor deposition (MOCVD). A peak electron mobility of $\sim 9500\space cm^{2}/V\space s$ is achieved at 45 K. Further investi…
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A new record-high room temperature electron Hall mobility ($μ_{RT} = 194\space cm^{2}/V\space s$ at $n\sim 8\times 10^{15}\space cm^{-3}$) for $β$-Ga2O3 is demonstrated in the unintentionally doped thin film grown on (010) semi-insulating substrate via metalorganic chemical vapor deposition (MOCVD). A peak electron mobility of $\sim 9500\space cm^{2}/V\space s$ is achieved at 45 K. Further investigation on the transport properties indicate the existence of sheet charges near the epi-layer/substrate interface. Si is identified as the primary contributor to the background carrier in both the epi-layer and the interface, originated from both surface contamination as well as growth environment. Pre-growth hydrofluoric acid cleaning of the substrate lead to an obvious decrease of Si impurity both at interface and in epi-layer. In addition, the effect of MOCVD growth condition, particularly the chamber pressure, on the Si impurity incorporation is studied. A positive correlation between the background charge concentration and the MOCVD growth pressure is confirmed. It is noteworthy that in a $β$-Ga2O3 film with very low bulk charge concentration, even a reduced sheet charge density can play an important role in the charge transport properties.
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Submitted 27 April, 2020;
originally announced April 2020.
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Metal$/BaTiO_{3}/β-Ga_{2}O_{3}$ Dielectric Heterojunction Diode with 5.7 MV/cm Breakdown Field
Authors:
Zhanbo Xia,
Hareesh Chandrasekar,
Wyatt Moore,
Caiyu Wang,
Aidan Lee,
Joe McGlone,
Nidhin Kurian Kalarickal,
Aaron Arehart,
Steven Ringel,
Fengyuan Yang,
Siddharth Rajan
Abstract:
Wide and ultra-wide band gap semiconductors can provide excellent performance due to their high energy band gap, which leads to breakdown electric fields that are more than an order of magnitude higher than conventional silicon electronics. In materials where p-type doping is not available, achieving this high breakdown field in a vertical diode or transistor is very challenging. We propose and de…
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Wide and ultra-wide band gap semiconductors can provide excellent performance due to their high energy band gap, which leads to breakdown electric fields that are more than an order of magnitude higher than conventional silicon electronics. In materials where p-type doping is not available, achieving this high breakdown field in a vertical diode or transistor is very challenging. We propose and demonstrate the use of dielectric heterojunctions that use extreme permittivity materials to achieve high breakdown field in a unipolar device. We demonstrate the integration of a high permittivity material BaTiO3 with n-type $β$-Ga2O3 to enable 5.7 MV/cm average electric field and 7 MV/cm peak electric field at the device edge, while maintaining forward conduction with relatively low on-resistance and voltage loss. The proposed dielectric heterojunction could enable new design strategies to achieve theoretical device performance limits in wide and ultra-wide band gap semiconductors where bipolar doping is challenging.
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Submitted 5 November, 2019;
originally announced November 2019.
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High electron density $β-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ modulation doping using ultra-thin (1 nm) spacer layer
Authors:
Nidhin Kurian Kalarickal,
Zhanbo Xia,
Joe Mcglone,
Yumo Liu,
Wyatt Moore,
Aaron Arehart,
Steve Ringel,
Siddharth Rajan
Abstract:
We report on the design and demonstration of $β-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ modulation doped heterostructures to achieve high sheet charge density. The use of a thin spacer layer between the Si delta-doping and heterojunction interface was investigated in $β-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ modulation doped structures. We find that that this strategy enables higher 2DEG sheet charge densi…
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We report on the design and demonstration of $β-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ modulation doped heterostructures to achieve high sheet charge density. The use of a thin spacer layer between the Si delta-doping and heterojunction interface was investigated in $β-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ modulation doped structures. We find that that this strategy enables higher 2DEG sheet charge density up to 6.1x10^12 cm^2 with mobility of 147 cm^2/Vs. The presence of a degenerate 2DEG channel was confirmed by the measurement of low temperature effective mobility of 378 cm^2/V-s and a lack of carrier freeze out from low temperature capacitance voltage measurements. The electron density of 6.1x10^12 cm^2 is the highest reported sheet charge density obtained without parallel conduction channels in an $(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ heterostructure system.
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Submitted 25 October, 2019;
originally announced October 2019.
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Mechanism of Si doping in Plasma Assisted MBE Growth of \b{eta}-Ga2O3
Authors:
Nidhin Kurian Kalarickal,
Zhanbo Xia,
Joe McGlone,
Sriram Krishnamoorthy,
Wyatt Moore,
Mark Brenner,
Aaron R. Arehart,
Steven A. Ringel,
Siddharth Rajan
Abstract:
We report on the origin of high Si flux observed during the use of Si as a doping source in plasma assisted MBE growth of \b{eta}-Ga2O3. We show on the basis of secondary ion mass spectroscopy (SIMS) analysis that Si flux is not limited by the vapor pressure of Si but by the formation of volatile SiO. The low sublimation energy of SiO leads to weak dependence of the SiO flux of Si cell temperature…
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We report on the origin of high Si flux observed during the use of Si as a doping source in plasma assisted MBE growth of \b{eta}-Ga2O3. We show on the basis of secondary ion mass spectroscopy (SIMS) analysis that Si flux is not limited by the vapor pressure of Si but by the formation of volatile SiO. The low sublimation energy of SiO leads to weak dependence of the SiO flux of Si cell temperature and a strong dependence on the background oxygen pressure. Extended exposure to activated oxygen results in reduction of SiO flux due to the formation of SiO2 on the Si surface. The work reported provides key understanding for incorporating Si into future oxide-based semiconductor heterostructure and device MBE growth.
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Submitted 2 August, 2019;
originally announced August 2019.
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Velocity Saturation in La-doped BaSnO3 Thin Films
Authors:
Hareesh Chandrasekar,
Junao Cheng,
Tianshi Wang,
Zhanbo Xia,
Nicholas G. Combs,
Christopher R. Freeze,
Patrick B. Marshall,
Joe McGlone,
Aaron Arehart,
Steven Ringel,
Anderson Janotti,
Susanne Stemmer,
Wu Lu,
Siddharth Rajan
Abstract:
BaSnO_{3}, a high mobility perovskite oxide, is an attractive material for oxide-based electronic devices. However, in addition to low-field mobility, high-field transport properties such as the saturation velocity of carriers play a major role in determining device performance. We report on the experimental measurement of electron saturation velocity in La-doped BaSnO_{3} thin films for a range o…
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BaSnO_{3}, a high mobility perovskite oxide, is an attractive material for oxide-based electronic devices. However, in addition to low-field mobility, high-field transport properties such as the saturation velocity of carriers play a major role in determining device performance. We report on the experimental measurement of electron saturation velocity in La-doped BaSnO_{3} thin films for a range of doping densities. Predicted saturation velocities based on a simple LO-phonon emission model using an effective LO phonon energy of 120 meV show good agreement with measurements of velocity saturation in La-doped BaSnO_{3} films.. Density-dependent saturation velocity in the range of 1.6x10^{7} cm/s reducing to 2x10^{6} cm/s is predicted for δ-doped BaSnO3 channels with carrier densities ranging from 10^{13} cm^{-2} to 2x10^{14} cm^{-2} respectively. These results are expected to aid the informed design of BaSnO3 as the active material for high-charge density electronic transistors.
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Submitted 3 August, 2019; v1 submitted 13 May, 2019;
originally announced May 2019.