Schottky barriers on n-GaN grown on SiC

Калинина, Е. В.; Kuznetsov, N. A.; Dimitriev, V.; Irvine, K. G.; Carter, C. H.

doi:10.1007/bf02666644

Cited by 97 publications

(60 citation statements)

References 4 publications

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“…Also, a slope of 0.97 has been reported for I-V and CV measurements on KOH-treated n-GaN grown on SiC. 44,45 For p-GaN ͓Fig. 9͑b͔͒, a slope with a value of ϳϪ0.8 was observed.…”

Section: Discussionmentioning

confidence: 86%

X-ray photoemission determination of the Schottky barrier height of metal contacts to n–GaN and p–GaN

Rickert

Ellis

Kim

et al. 2002

Journal of Applied Physics

105

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Synchrotron radiation-based x-ray photoemission spectroscopy was used to study the surface Fermi level position within the band gap for thin metal overlayers of Au, Al, Ni, Ti, Pt, and Pd on n-GaN and p-GaN. Nonequilibrium effects were taken into account by measuring the Fermi edge of the metal overlayer. There are two different behaviors observed for the six metals studied. For Au, Ti, and Pt, the surface Fermi level lies about 0.5-eV higher in the gap for n-type than for p-type GaN. For Ni, Al, and Pd, the surface Fermi level position is independent of doping, but varies from one metal to the other. Results for Ni, Pd, and Al fit a modified Schottky-Mott theory, while Au, Ti, and Pt demonstrate a more complex behavior. Atomic force microscopy was used along with photoemission to investigate the growth mode of each metal on the GaN surface.

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“…Also, a slope of 0.97 has been reported for I-V and CV measurements on KOH-treated n-GaN grown on SiC. 44,45 For p-GaN ͓Fig. 9͑b͔͒, a slope with a value of ϳϪ0.8 was observed.…”

Section: Discussionmentioning

confidence: 86%

X-ray photoemission determination of the Schottky barrier height of metal contacts to n–GaN and p–GaN

Rickert

Ellis

Kim

et al. 2002

Journal of Applied Physics

105

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“…These results are consistent with electrical measurements in the literature. [7][8][9] Table II shows the previously determined surface barrier height on n-GaN surfaces treated with KOH or HCl. The barriers are determined by either I -V or C -V. The barrier height for the HCl-treated sample is consistently lower with either technique for Au or Ni Schottky diodes.…”

Section: As-receivedmentioning

confidence: 99%

n- GaN surface treatments for metal contacts studied via x-ray photoemission spectroscopy

Rickert¹,

Ellis²,

Himpsel³

et al. 2002

Applied Physics Letters

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The surface chemistry and electronic properties of n-GaN surfaces were studied via x-ray photoemission spectroscopy before and after wet chemical treatments. Shifts of the surface Fermi level were measured with the change in position of the Ga 3d core level peak. HCl treatment of n-GaN led to a 0.9 eV shift of the surface Fermi level toward the conduction band minimum, while KOH treatment led to a 0.3 eV shift of the surface Fermi level toward the valance band maximum. These shifts lead to a reduction in the surface barrier for HCl-treated n-GaN and for KOH-treated p-GaN, potentially improving contact resistance. The changes in surface chemistry indicate that a N (or Ga) deficiency with HCl(KOH) treatment alters the surface state density through the formation of donor (acceptor)-like states.

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“…Since the thickness of the standoff region sets the resistivity of the device, it will determine power dissipation and maximum current density of the device. 2,3 In previous studies, Schottky diodes have been fabricated on GaN using a variety of elemental metals including Pd and Pt, 4,5 , Au, Cr, and Ni,6,7 , and Mo and W. 8 More details on the metal-GaN contact technology can be found in Ref. 9.…”

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confidence: 99%

High voltage (450 V) GaN Schottky rectifiers

Bandić

Bridger

Piquette

et al. 1999

Applied Physics Letters

151

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We fabricated high standoff voltage ͑450 V͒ Schottky rectifiers on hydride vapor phase epitaxy grown GaN on sapphire substrate. Several Schottky device geometries were investigated, including lateral geometry with rectangular and circular contacts, mesa devices, and Schottky metal field plate overlapping a SiO 2 layer. The best devices were characterized by an ON-state voltage of 4.2 V at a current density of 100 A/cm 2 and a saturation current density of 10 Ϫ5 A/cm 2 at a reverse bias of 100 V. From the measured breakdown voltage we estimated the critical field for electric breakdown in GaN to be (2.2Ϯ0.7)ϫ10 6 V/cm. This value for the critical field is a lower limit since most of the devices exhibited abrupt and premature breakdown associated with corner and edge effects. © 1999 American Institute of Physics. ͓S0003-6951͑99͒02409-2͔Wide band gap materials, primarily SiC and GaN, have recently attracted a lot of interest for applications in high power and high temperature electronics. Although the processing technology for SiC is more mature, GaN offers several advantages. First, there are various device possibilities using GaN/AlGaN heterojunctions which are not available in the SiC system. Second, the availability of cheap and efficient hydride vapor phase epitaxy ͑HVPE͒ growth technology achieving growth rates in excess of 100 m/h, have produced thick, high quality GaN layers on sapphire. 1 Third, by using AlGaN layers, one can take advantage of a larger band gap to achieve higher critical electric fields than in GaN alone.In this study, we focus on the fabrication of high voltage, GaN based Schottky rectifiers and the measurement of the critical field for electric breakdown. The critical field for electric breakdown is one of the most significant parameters in the design and performance of high power devices. It directly influences the required thickness of the standoff region in the Schottky rectifier and bipolar devices, such as the thyristor. Since the thickness of the standoff region sets the resistivity of the device, it will determine power dissipation and maximum current density of the device. 2,3 In previous studies, Schottky diodes have been fabricated on GaN using a variety of elemental metals including Pd and Pt, 4,5 , Au, Cr, and Ni,6,7 , and Mo and W. 8 More details on the metal-GaN contact technology can be found in Ref. 9.In this work, Schottky rectifiers were fabricated on 8-10 m thick GaN layers grown by HVPE on sapphire, where the electron concentration changes with the distance from the GaN/sapphire interface. We carried out conductivity and Hall measurements on a series of HVPE GaN films of varying thickness ranging from 0.07 to 9.2 m, and fitted the data to a two layer model. [10][11][12][13] From the model, we concluded that the GaN films consisted of a low conductivity, low electron concentration, 8-10 m thick top layer on a very thin (Ͻ100 nm), highly conductive, high electron concentration bottom layer. The electron concentrations and mobilities in the thin interface layer and thic...

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Schottky barriers on n-GaN grown on SiC

Cited by 97 publications

References 4 publications

X-ray photoemission determination of the Schottky barrier height of metal contacts to n–GaN and p–GaN

X-ray photoemission determination of the Schottky barrier height of metal contacts to n–GaN and p–GaN

n- GaN surface treatments for metal contacts studied via x-ray photoemission spectroscopy

High voltage (450 V) GaN Schottky rectifiers

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