Schottky barrier on <i>n</i>-type GaN grown by hydride vapor phase epitaxy

Hacke, Peter; Detchprohm, Theeradetch; Hiramatsu, Kazumasa; Sawaki, Nobuhiko

doi:10.1063/1.110417

Cited by 283 publications

(173 citation statements)

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“…Previous reports have attributed variations in the fitted Richardson constant to enhanced tunneling current, interfacial oxide layers, or lateral Schottky barrier height variation. [17][18][19][20][21][22][23] However, since we find that the current of the higher TDD sample is always lower than the current of the lower TDD sample at all forward bias voltages, it is unlikely that tunneling is responsible for the deviation, since an additional parallel transport mechanism will only add current in forward bias as would any regions of reduced barrier heights associated with the higher dislocation density. The similarity of the barrier heights and ideality factors for both types of samples supports the assertion that tunneling is negligible and that an interfacial layer is absent.…”

Section: B Reconciliation Of the Richardson Constant And Impact Of Tmentioning

confidence: 87%

“…It shows that a review of the literature reveals many reports of large variations in the extracted Richardson constant for n-GaN Schottky diodes using simple I-V models with reported values ranging from 0.006 to 102 A K −2 cm −2 . [17][18][19] This large variation is reported despite the fact that the Richardson constant is a fundamental parameter that depends only on the semiconductor material constants, and thus should not display significant dependencies on Schottky metal, TDD, etc. This calls into question the simple extraction of Richardson constants as is commonly done in I-V analysis as described in Sec.…”

Section: B Reconciliation Of the Richardson Constant And Impact Of Tmentioning

confidence: 99%

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Effect of threading dislocation density on Ni∕n-GaN Schottky diode I-V characteristics

Arehart

Moran

Speck

et al. 2006

Journal of Applied Physics

110

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The impact of threading dislocation density on Ni/ n-GaN Schottky barrier diode characteristics is investigated using forward biased current-voltage-temperature ͑I-V-T͒ and internal photoemission ͑IPE͒ measurements. Nominally, identical metal-organic chemical vapor deposition grown GaN layers were grown on two types of GaN templates on sapphire substrates to controllably vary threading dislocation density ͑TDD͒ from 3 ϫ 10 7 to 7 ϫ 10 8 cm −2 . I-V-T measurements revealed thermionic emission to be the dominant transport mechanism with ideality factors near 1.01 at room temperature for both sample types. The Schottky barrier heights showed a similar invariance with TDD, with measured values of 1.12-1.13 eV obtained from fitting the I-V-T results to a thermionic emission-diffusion model. The I-V-T results were verified by IPE measurements made on the same diodes, confirming that the Ni/ n-GaN barrier heights do not show a measurable TDD dependence for the TDD range measured here. In apparent contrast to this result is that the measured forward bias I-V characteristics indicate a shift in the observed forward bias turn-on voltage such that at the higher TDD value investigated here, a larger turn-on voltage ͑lower current͒ is observed. This difference is attributed to localized current blocking by high potential barrier regions surrounding threading dislocations that intersect the Ni/ GaN interface. A simple model is presented that reconciles both the observed voltage shift and variations in the extracted Richardson constant as a function of threading dislocation density. With this model, an average local barrier surrounding dislocation of ϳ0.2 V is obtained, which diverts current flow across the forward biased Schottky interface to nondislocated regions.

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Section: B Reconciliation Of the Richardson Constant And Impact Of Tmentioning

confidence: 87%

Section: B Reconciliation Of the Richardson Constant And Impact Of Tmentioning

confidence: 99%

Effect of threading dislocation density on Ni∕n-GaN Schottky diode I-V characteristics

Arehart

Moran

Speck

et al. 2006

Journal of Applied Physics

110

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“…From thermionic emission theory, I 0 is given by The significant difference could be due to the existence of a very thin SiO 2 barrier at the ZnO:N/ p-Si interface, through which the electrons must tunnel, as discussed by Hacke et al in connection with the much lower value of A ‫ء‬ found on n-GaN Schottky barrier diodes. 13 Interestingly, the forward current at higher biases, where the current is limited by series resistance, decreases as temperature decreases. The reason may well involve carrier freeze-out in the ZnO:N layer, which has been confirmed by temperature-dependent measurements of dark current in a ZnO:N layer grown on sapphire in a separate run.…”

Section: Resultsmentioning

confidence: 99%

Electron and hole traps in N-doped ZnO grown on p-type Si by metalorganic chemical vapor deposition

Fang

Claflin

Kerr

et al. 2007

Journal of Applied Physics

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Electron and hole traps in N-doped ZnO were investigated using a structure of n + -ZnO:Al/ i-ZnO/ ZnO:N grown on a p-Si substrate by metalorganic chemical vapor deposition ͑for growth of the ZnO:N layer͒ and sputtering deposition ͑for growth of the i-ZnO and n + -ZnO:Al layers͒. Current-voltage and capacitance-voltage characteristics measured at temperatures from 200 to 400 K show that the structure is an abrupt n + − p diode with very low leakage currents. By using deep level transient spectroscopy, two hole traps, H3 ͑0.35 eV͒ and H4 ͑0.48 eV͒, are found in the p-Si substrate, while one electron trap E3 ͑0.29 eV͒ and one hole trap H5 ͑0.9 eV͒ are observed in the thin ZnO:N layer. Similarities to traps reported in the literature are discussed.

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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

153

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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 barrier on n-type GaN grown by hydride vapor phase epitaxy

Cited by 283 publications

References 5 publications

Effect of threading dislocation density on Ni∕n-GaN Schottky diode I-V characteristics

Effect of threading dislocation density on Ni∕n-GaN Schottky diode I-V characteristics

Electron and hole traps in N-doped ZnO grown on p-type Si by metalorganic chemical vapor deposition

High voltage (450 V) GaN Schottky rectifiers

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