High temperature stability of chromium boride ohmic contacts to p-type 6H-SiC

Oder, Tom; Williams, John R.; Bozack, Michael J.; Iyer, Venkatesh; Mohney, Suzanne E.; Crofton, J.

doi:10.1007/s11664-998-0409-4

Cited by 22 publications

(9 citation statements)

References 22 publications

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“…In the investigation of thermally stable ohmic contact to p-type SiC using CrB 2 , Oder et al reported the removal of a significant amount of O 2 from the CrB 2 /SiC interface in the form of volatile B 2 O 3 following high-temperature annealing. 40,41 Similar removal of O 2 was also reported during the intentional oxidation of TiB 2 , where B 2 O 3 was observed to form and evaporate rapidly at high temperatures. 42 We believe that the removal of O 2 from the ZrB 2 /SiC interface similarly occurs in the form of oxides such as B 2 O 3 or H 3 BO 3 known to be volatile at 300°C.…”

Section: Resultssupporting

confidence: 65%

Improved Schottky Contacts on n-Type 4H-SiC Using ZrB2 Deposited at High Temperatures

Oder

Martin

Adedeji

et al. 2007

Journal of Elec Materi

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We report on improved electrical properties and thermal stability of ZrB 2 Schottky contacts deposited on n-type 4H-SiC at temperatures between 20°C and 800°C. The Schottky barrier heights (SBHs) determined by current-voltage measurements increased with deposition temperature, from 0.87 eV for contacts deposited at 20°C to 1.07 eV for those deposited at 600°C. The Rutherford backscattering spectroscopy (RBS) spectra of these contacts revealed a decrease in oxygen peak with an increase in the deposition temperature and showed no reaction at the ZrB 2 /SiC interface. These results indicate improved electrical and thermal properties of ZrB 2 /SiC Schottky contacts, making them attractive for high-temperature applications.

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Section: Resultssupporting

confidence: 65%

Improved Schottky Contacts on n-Type 4H-SiC Using ZrB2 Deposited at High Temperatures

Oder

Martin

Adedeji

et al. 2007

Journal of Elec Materi

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“…Although the principal mechanisms are uncertain, it is interesting to calculate the effects of Ge as if they were fully ascribed to a reduction in the metal-semiconductor barrier height. The barrier lowering can be estimated using a model of thermionic emission, 17 for which the specific contact resistivity is (4) where B is the metal-semiconductor barrier height, kT is the thermal voltage, A* is the effective Richardson's constant, and q is the electronic charge. 18 Based upon the c values in Table I, the calculated reduction in barrier height was 57 mV for the n-type SiC:Ge and 70 mV for the p-type SiC:Ge.…”

Section: Discussionmentioning

confidence: 99%

“…1,2 As a large-bandgap semiconductor, SiC does not easily form low-resistance contacts to metals, especially for p-type. 3,4 For example, with metals, such as Ni, quality ohmic contacts to p-SiC have not yet been achieved. 5 By careful preparation, specific contact resistivities near 10 Ϫ5 ⍀cm 2 have been obtained with Ni to n-type SiC and Ti/Al to p-type SiC.…”

Section: Background/introductionmentioning

confidence: 99%

A technique to reduce the contact resistance to 4H-silicon carbide using germanium implantation

Katulka

Roe

Kolodzey

et al. 2002

Journal of Elec Materi

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The effects of implanted Ge on the resistance of nickel-metal contacts to n-type and p-type 4H-SiC are reported. The Ge was implanted with an energy of 346 keV and a dose of 1.7 ϫ 10 16 cm Ϫ2 , and the wafer was annealed up to 1700°C for 30 min. Contact resistance measurements using the transfer length method (TLM) were performed on etched mesas of n-type and p-type 4H-SiC, with and without the Ge. For the annealed-Ni metal contacts, the Ge lowered the specific contact resistivity from 5.3 ϫ 10 Ϫ4 ⍀cm 2 to 6.0 ϫ 10 Ϫ5 ⍀cm 2 for ntype SiC and from 1.2 ϫ 10 Ϫ3 ⍀cm 2 to 8.3 ϫ 10 Ϫ5 ⍀cm 2 for p-type SiC. For the as-deposited (unannealed) Ni, the Ge produced ohmic contacts, whereas the contacts without Ge were rectifying. These results suggest that the addition of Ge can be an important process step to reduce the contact resistance for SiCdevice applications.

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“…The escape of oxygen in the form of volatile B 2 O 3 has been reported in the investigations of CrB 2 and TiB 2 films. 21,22 We propose that in the boride contacts we have studied, oxygen similarly escapes by way of oxides such as B 2 O 3 or H 3 BO 3 known to be volatile at 300°C, when these borides are deposited on SiC substrates held at 400°C and above. 23 Since the presence of impurities such as oxygen at the interface is known to contribute to undesirable electrical characteristics, the improvement in the barrier properties of the boride/SiC contacts is possibly due to the escape of oxygen from the metal/SiC interface.…”

Section: ͑2͒mentioning

confidence: 99%

Ideal SiC Schottky barrier diodes fabricated using refractory metal borides

Oder¹,

Sutphin²,

Kummari³

2009

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Several refractory metal borides were used as Schottky contacts to fabricate n-type 4H-SiC Schottky diodes. The boride contacts were deposited on SiC substrates held at 20 and 600 °C. Contacts deposited on substrates held at 600 °C produced better diodes with smaller ideality factors from 1.05 to 1.10, barrier heights from 0.94 to 1.15 eV, smaller leakage current densities at a reverse bias of 15 V, and smaller specific on-resistances compared to contacts deposited on substrates held at 20 °C, and these values remained essentially unchanged after annealing at 600 °C for 20 min. The Rutherford backscattering spectroscopy spectra of one of these boride contacts revealed a systematic decrease in oxygen with an increase in the deposition temperature. The improved electrical properties and thermal stability make these boride contacts attractive for high power and high temperature device applications.

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High temperature stability of chromium boride ohmic contacts to p-type 6H-SiC

Cited by 22 publications

References 22 publications

Improved Schottky Contacts on n-Type 4H-SiC Using ZrB2 Deposited at High Temperatures

Improved Schottky Contacts on n-Type 4H-SiC Using ZrB2 Deposited at High Temperatures

A technique to reduce the contact resistance to 4H-silicon carbide using germanium implantation

Ideal SiC Schottky barrier diodes fabricated using refractory metal borides

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