High barrier height GaN Schottky diodes: Pt/GaN and Pd/GaN

Wang, Lei; Nathan, M. I.; Lim, T.; Khan, M. Asif; Chen, Q.

doi:10.1063/1.115948

Cited by 248 publications

(142 citation statements)

References 11 publications

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“…Schottky barrier diodes (SBD) are the choice structure for many semiconductor devices, including microwave diodes, fieldeffect transistors and photodiodes [2][3][4]. Their technological importance requires a full understanding of the nature of the electrical characteristics of SBDs.…”

Section: Introductionmentioning

confidence: 99%

Effects of chemical treatment on barrier height and ideality factors of Au/GaN Schottky diodes

Diale

Auret

2009

Physica B: Condensed Matter

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a b s t r a c tWe have studied Au/n-GaN Schottky barrier diodes. GaN surfaces have been prepared by cleaning in HCl and (NH 4 ) 2 S prior to metal deposition. The zero-biased barrier heights and ideality factors obtained from the current-voltage characteristics differ from diode to diode, although all the samples were prepared identically. The statistical analysis for the reverse bias C-V data yielded mean value of (1.357 0.04) eV for Schottky barrier height of HCl treated sample and (1.20 7 0.03) eV for (NH 4 ) 2 S sample, where 9 dots were considered from each cleaning method. It was found that the barrier height values obtained from the C À 2 -V (1.43 eV) and I-V characteristics (0.89 eV) are different from each other by 0.54 eV. The inhomogeneous barrier heights were found to be related to the effect of the high series resistance on diode parameters [1].

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Section: Introductionmentioning

confidence: 99%

Effects of chemical treatment on barrier height and ideality factors of Au/GaN Schottky diodes

Diale

Auret

2009

Physica B: Condensed Matter

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“…13 Schottky contacts on n-type GaN have not received much attention yet. Au ͑as-deposited͒, 3,14 Pt and Pd, 1,[15][16][17] Ni, 13,18 and PtSi 19 were reported to have rectifying characteristics. Platinum with its high work function of 5.65 eV 20 exhibits ideal Schottky behavior on n-type GaN with a high barrier height.…”

Section: Introductionmentioning

confidence: 99%

Thermal reaction of Pt film with 〈110〉 GaN epilayer

Gasser

Kolawa

Nicolet

1999

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Backscattering spectrometry, x-ray diffractometry, and scanning electron microscopy have been used to study the reaction of a thin Pt film with an epilayer of ͗110͘ GaN on ͗110͘ sapphire upon annealing at 450, 550, 650, 750, and 800°C for 30 min. A Ga concentration of 2 at. % is detected by MeV 4 He ϩϩ backscattering spectrometry in the Pt layer at 550°C. By x-ray diffraction, structural changes are observed already at 450°C. At 650°C, textured Ga 2 Pt appears as reaction product. The surface morphology exhibits instabilities by the formation of blisters at 650°C and voids at 800°C.

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“…Mg. Thus we can safely assume that our GaN NW is n-type.Since Pt is normally used for Schottky barrier contacts on n-type GaN, 6 we were surprised to find low resistance and linear I-V from our FIB-Pt contacts. This is under further investigation, but we suspect that Ga + I-beam irradiation around the contact area plays a role.…”

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confidence: 99%

“…It is surprising for FIB patterned Pt to form low resistance ohmic contacts on n-type GaN since Pt generally forms a Schottky barrier on n-type GaN. 6 In the second part of this letter we exploit the same spatial selectivity to create patterned Pt nano-catalysts, which constrain GaN NW nucleation to these small selected regions. …”

mentioning

confidence: 99%

Focused-ion-beam platinum nanopatterning for GaN nanowires: Ohmic contacts and patterned growth

Nam

Kim

Fischer

2005

Applied Physics Letters

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Nanopatterned Pt by Ga + focused ion beam (FIB) decomposition of an organometallic precursor forms low resistance ohmic contacts on 40-70 nm diameter GaN nanowires (NWs) grown by thermal reaction of Ga 2 O 3 and NH 3 . With no intentional doping, the wires are presumed to be n-type. Thus, the linear I-V behavior is surprising since evaporated Pt usually forms Schottky barriers on n-GaN. Ohmic behavior was not obtained for 130-140 diameter wires, even with thicker Pt contacts. A second application of FIB Pt nanopatterning was demonstrated by position-selective growth of GaN NWs on Pt catalyst dots. NW locations and density are defined by the position, size, and thickness of the Pt deposit. Combining these techniques provides a versatile platform for nanostructure research and development. Letters, Volume 86, Article 193112, 2005, 3 Achieving reliable low resistance ohmic contacts to GaN is not trivial. High contact resistance often degrades the performance of GaN-based devices. 1 Low resistance ohmic contacts to n-type GaN are generally obtained by Ti deposition and conventional lithography. Similar metals and methods have been applied to GaN NWs, 2,3 but these require a tedious sequence of locating NWs on a substrate by atomic force microscopy (AFM), defining a contact pattern with e-beam lithography, metal deposition and removal of e-beam resist. In addition, achieving robust ohmic contacts requires work function tuning and deposition of an adhesion layer to insure mechanical stability. Attracted by its convenience and versatility, several groups reported the use of direct Pt deposition by focused ion beam (FIB) to make metal contacts on Bi and Ag NWs 4,5 and carbon nanotubes 5 . This is done by locally decomposing a fine jet of organometallic vapor with the highly focused and spatially controlled Ga + ion beam (I-beam). 5 Since most FIB systems are also equipped with high resolution scanning electron microscopy (SEM), the combination provides unique capabilities of fast and precise metal contact patterning. Here we demonstrate direct FIB nanopatterning of low resistance ohmic Pt contacts on n-type GaN NWs grown by Ga 2 O 3 -NH 3 reaction without intentional doping. It is surprising for FIB patterned Pt to form low resistance ohmic contacts on n-type GaN since Pt generally forms a Schottky barrier on n-type GaN. 6 In the second part of this letter we exploit the same spatial selectivity to create patterned Pt nano-catalysts, which constrain GaN NW nucleation to these small selected regions. Comments Postprint version. Published in Applied PhysicsThe details of GaN NW synthesis are described in a previous report. 7 We used sputter-deposited Au/Pd catalyst layers on Si substrates. Two different layer thicknesses yielded two different NW diameters, i.e. 40-70 nm and 130-140 nm, with which we could study the effect of NW diameter on I-V characteristics. NWs were then transferred to 200 nm SiO x on Si chips with Cr/Au (10 µm/50 µm) contact pads predeposited by e-beam lithography and thermal evaporation. Th...

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High barrier height GaN Schottky diodes: Pt/GaN and Pd/GaN

Cited by 248 publications

References 11 publications

Effects of chemical treatment on barrier height and ideality factors of Au/GaN Schottky diodes

Effects of chemical treatment on barrier height and ideality factors of Au/GaN Schottky diodes

Thermal reaction of Pt film with 〈110〉 GaN epilayer

Focused-ion-beam platinum nanopatterning for GaN nanowires: Ohmic contacts and patterned growth

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