Band alignment and electrical properties of Al2O3/<i>β</i>-Ga2O3 heterojunctions

Kamimura, Takafumi; Sasaki, Kohei; Wong, Man Hoi; Krishnamurthy, Daivasigamani; Kuramata, Akito; Masui, Takekazu; Yamakoshi, Shigenobu; Higashiwaki, Masataka

doi:10.1063/1.4876920

Cited by 188 publications

(102 citation statements)

References 23 publications

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“…15 To our knowledge, this is the first report of a positive threshold voltage measured for a β-Ga 2 O 3 MOS interface, and presently speculate that it originated from a larger conduction band offset between HfO 2 and β-Ga 2 O 3 , beyond the values of 3.1 ± 0.2 eV and 1.5 ± 0.2 eV reported for the SiO 2 and Al 2 O 3 interfaces with Ga 2 O 3 , respectively. 13,14 Further X-ray photoelectron spectroscopy measurements will be performed to accurately determine the band offsets for this novel dielectric interface.…”

Section: Resultsmentioning

confidence: 99%

“…We also utilized a high-k HfO 2 gate dielectric process, as only SiO 2 and Al 2 O 3 have been reported to-date. 13,14 Experimental A thin sliver of Ga 2 O 3 was cleaved along the (001) face of an on-axis (−201), non-intentionally n-type doped (∼3 × 10 17 cm −3 ) commercial Ga 2 O 3 substrate (Tamura Corporation) produced by the edge-defined film fed (EFF) growth method. The cleaved material was verified to be of the (001) orientation by X-ray diffraction (XRD, Fig.…”

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confidence: 99%

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Editors' Choice Communication—A (001) β-Ga₂O₃MOSFET with +2.9 V Threshold Voltage and HfO₂Gate Dielectric

Tadjer

Mahadik

Wheeler

et al. 2016

ECS J. Solid State Sci. Technol.

130

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An MOS transistor fabricated on (001) β-Ga 2 O 3 exfoliated from a commercial (−201) β-Ga 2 O 3 substrate is reported. A maximum drain current of 11.1 mA/mm was measured, and a non-destructive breakdown was reached around 80 V in the off state. Threshold voltage of +2.9 V was extracted at 0.1 V drain bias, and peak transconductance of 0.18 mS/mm was measured at V DS = 1 V, corresponding to a field effect mobility of 0.17 cm 2 /Vs. Hall effect and electron spin resonance data suggested that electron conductivity was due primarily to O vacancy donors (V O + ) with an estimated density of 2. The single-crystal monoclinic (β) phase of Ga 2 O 3 is an advantageous material for high-power, high-temperature electronic device applications due to its high energy gap (4.8-4.9 eV) and high breakdown field (8 MV/cm), yielding a nearly ten-fold higher Baliga figure of merit than that of 4H-SiC (BFOM Ga 2 O 3 = 3444, BFOM 4H-SiC = 300).1 Commercially available β-Ga 2 O 3 substrates enable the epitaxial growth of low defect density epitaxial β-Ga 2 O 3 by a number of methods, including chemical vapor deposition, hydride vapor phase epitaxy (HVPE), and molecular beam epitaxy (MBE), among others.2-6 Schottky barrier diodes (SBDs) based on Ga 2 O 3 have exhibited very low turn on voltage and reverse leakage current, suggesting that unintentionally doped Ga 2 O 3 has extremely low generation/recombination rates and thus a high photoconductive gain.7 Advances in doping control have enabled exceptional early reports of metal-and metal-insulatorgated field effect transistors (MOSFETs). Wong et al. demonstrated a field-plated β-Ga 2 O 3 MOSFET with a breakdown voltage of over 750 V using a Si-implanted channel.8 Most recently, Green and coworkers have reported a Ga 2 O 3 MOSFET with a Sn-doped channel and a 0.6 μm gate-drain spacing to operate at 200 V drain bias, experimentally demonstrating gate-drain fields in excess of 3 MV/cm. 9This excellent progress has positioned Ga 2 O 3 as a viable candidate for next generation material for power applications. However, no demonstration of normally-off operation, a key requirement for fail-safe operation of power switches, has been achieved or proposed to-date.From a practical perspective, development of Ga 2 O 3 transistors has been limited by the availability of device-quality epitaxial films. For this reason, early reports have exploited the relatively large a-plane lattice constant of β-Ga 2 O 3 (1.2 nm) in order to mechanically exfoliate thin films from the (001) plane of a substrate using the scotch tape method to fabricate back-gated devices. 10,11 We employed a similar method to transfer a thin (∼300 nm) Ga 2 O 3 flake onto a SiO 2 /Si substrate, 12 and performed a standard top-side insulated-gate process to fabricate a three-terminal device. We also utilized a high-k HfO 2 gate dielectric process, as only SiO 2 and Al 2 O 3 have been reported to-date. 13,14Experimental A thin sliver of Ga 2 O 3 was cleaved along the (001) face of an on-axis (−201), non-intentionally n-type doped (∼3 ×...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Editors' Choice Communication—A (001) β-Ga₂O₃MOSFET with +2.9 V Threshold Voltage and HfO₂Gate Dielectric

Tadjer

Mahadik

Wheeler

et al. 2016

ECS J. Solid State Sci. Technol.

130

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“…[12][13][14][15][16] Among the five structures of Ga 2 O 3 single crystal, monoclinic b-Ga 2 O 3 is the most stable one. Some preliminary studies on the material growth and power device fabrication and characterization have been carried out in the last several years.…”

Section: -10mentioning

confidence: 99%

Schottky barrier diode based on β-Ga2O3 (100) single crystal substrate and its temperature-dependent electrical characteristics

Dong

et al. 2017

Applied Physics Letters

148

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The Pt/β-Ga2O3 Schottky barrier diode and its temperature-dependent current-voltage characteristics were investigated for power device application. The edge-defined film-fed growth (EFG) technique was utilized to grow the (100)-oriented β-Ga2O3 single crystal substrate that shows good crystal quality characterized by X-ray diffraction and high resolution transmission electron microscope. Ohmic and Schottky electrodes were fabricated by depositing Ti and Pt metals on the two surfaces, respectively. Through the current-voltage (I-V) measurement under different temperature and the thermionic emission modeling, the fabricated Pt/β-Ga2O3 Schottky diode was found to show good performances at room temperature, including rectification ratio of 1010, ideality factor (n) of 1.1, Schottky barrier height (ΦB) of 1.39 eV, threshold voltage (Vbi) of 1.07 V, ON-resistance (RON) of 12.5 mΩ·cm2, forward current density at 2 V (J@2V) of 56 A/cm2, and saturation current density (J0) of 2 × 10−16 A/cm2. The effective donor concentration Nd − Na was calculated to be about 2.3 × 1014 cm3. Good temperature dependent performance was also found in the device. The Schottky barrier height was estimated to be about 1.3 eV–1.39 eV at temperatures ranging from room temperature to 150 °C. With increasing temperature, parameters such as RON and J@2V become better, proving that the diode can work well at high temperature. The EFG grown β-Ga2O3 single crystal is a promising material to be used in the power devices.

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“…Nevertheless the type-I band lineup is expected from the result. The type-I band lineup has been reported for amorphous Al 2 O 3 /β-Ga 2 O 3 interface [34] and β-(Al x Ga 1 À x ) 2 O 3 /β-Ga 2 O 3 interface [35], and is favorable not only for heterojunction transistor applications but also for multiple quantum wells of optical functions.…”

Section: Growth Of α-(Almentioning

confidence: 99%

Growth characteristics of corundum-structured α-(Al Ga1−)2O3/Ga2O3 heterostructures on sapphire substrates

Kaneko

Suzuki

Ito

et al. 2016

Journal of Crystal Growth

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Band alignment and electrical properties of Al2O3/β-Ga2O3 heterojunctions

Cited by 188 publications

References 23 publications

Editors' Choice Communication—A (001) β-Ga₂O₃MOSFET with +2.9 V Threshold Voltage and HfO₂Gate Dielectric

Editors' Choice Communication—A (001) β-Ga₂O₃MOSFET with +2.9 V Threshold Voltage and HfO₂Gate Dielectric

Schottky barrier diode based on β-Ga2O3 (100) single crystal substrate and its temperature-dependent electrical characteristics

Growth characteristics of corundum-structured α-(Al Ga1−)2O3/Ga2O3 heterostructures on sapphire substrates

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Band alignment and electrical properties of Al2O3/β-Ga2O3 heterojunctions

Cited by 188 publications

References 23 publications

Editors' Choice Communication—A (001) β-Ga2O3MOSFET with +2.9 V Threshold Voltage and HfO2Gate Dielectric

Editors' Choice Communication—A (001) β-Ga2O3MOSFET with +2.9 V Threshold Voltage and HfO2Gate Dielectric

Schottky barrier diode based on β-Ga2O3 (100) single crystal substrate and its temperature-dependent electrical characteristics

Growth characteristics of corundum-structured α-(Al Ga1−)2O3/Ga2O3 heterostructures on sapphire substrates

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Product

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Editors' Choice Communication—A (001) β-Ga₂O₃MOSFET with +2.9 V Threshold Voltage and HfO₂Gate Dielectric

Editors' Choice Communication—A (001) β-Ga₂O₃MOSFET with +2.9 V Threshold Voltage and HfO₂Gate Dielectric