The Schottky-barrier height of Au on n-Ga1−xAlxAs as a function of AlAs content

Best, J. S.

doi:10.1063/1.90850

Cited by 83 publications

(17 citation statements)

References 10 publications

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“…Figure 1 shows the structure of a typical BEEM sample. We used highly doped (nϭ1ϫ10 18 cm Ϫ3 ) epi-ready GaAs ͑100͒ wafers as substrates to ensure that samples would be conductive enough in subsequent BEEM experiments. Following oxide desorption under As over pressure, a buffer layer with a tapered doping profile was grown.…”

Section: Methodsmentioning

confidence: 99%

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Mapping of AlxGa1−xAs band edges by ballistic electron emission spectroscopy

Cheng

Collins

McGill

1997

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

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We have employed ballistic electron emission microscopy ͑BEEM͒ to study the energy positions in the conduction band of Al x Ga 1Ϫx As. Epilayers of undoped Al x Ga 1Ϫx As were grown by molecular beam epitaxy on conductive GaAs substrates. The Al composition x took on values of 0, 0.11, 0.19, 0.25, 0.50, 0.80 and 1 so that the material was examined in both the direct and indirect band gap regime. The Al x Ga 1Ϫx As layer thickness was varied from 100 to 500 Å to ensure probing of bulk energy levels. Different capping layers and surface treatments were explored to prevent surface oxidation and examine Fermi level pinning at the cap layer/Al x Ga 1Ϫx As interface. All samples were metallized ex situ with a 100 Å Au layer so that the final BEEM structure is of the form Au/capping layer/Al x Ga 1Ϫx As/bulk GaAs. Notably we have measured the Schottky barrier height for Au on Al x Ga 1Ϫx As. We have also probed the higher lying band edges such as the X point at low Al concentrations and the L point at high Al concentrations. Variations of these critical energy positions with Al composition x were mapped out in detail and compared with findings from other studies. Local variations of these energy positions were also examined and found to be on the order of 30-50 meV. The results of this study suggest that BEEM can provide accurate positions for multiple energy levels in a single semiconductor structure.

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Section: Methodsmentioning

confidence: 99%

“…Differences as much as 150 meV have been cited. 4 There is also a lack of consensus about the Au/Al x Ga 1Ϫx As Schottky barrier height at different Al concentrations, 17,18 which can be partly attributed to the various sample preparation procedures available.…”

Section: Introductionmentioning

confidence: 99%

Mapping of AlxGa1−xAs band edges by ballistic electron emission spectroscopy

Cheng

Collins

McGill

1997

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

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“…18 However, ideality factors of metal-Al x Ga 1Ϫx As contacts, exposed to air during device fabrication, were in the range of 1.15-1.3. 26,27 Furthermore, ideality factors were increased up to 1.68 after annealing at 300°C. 27 The devices used in this work were annealed at 300°C for 10 h for the enhancement of thermal stability.…”

Section: Discussionmentioning

confidence: 99%

“…25,26 It was observed that the Ga-O bond is stronger than that of As-O and that Ga atoms preferentially migrate towards the surface leaving vacancies behind in the subsurface region. This behavior can convert the subsurface layer into an Asenriched one.…”

Section: Discussionmentioning

confidence: 99%

Surface states on n-type Al0.24Ga0.76As characterized by deep-level transient spectroscopy

Choi

Lee

2001

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

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Articles you may be interested inSurface states on n-type Al 0.24 Ga 0.76 As were studied using capacitance deep-level transient spectroscopy ͑DLTS͒. Two types of hole-like traps ͑labeled as H1 and H2 in this work͒ were observed in a Al 0.24 Ga 0.76 As/In 0.22 Ga 0.78 As pseudomorphic high-electron-mobility transistor with a multifinger gate. But, no hole-like traps were observed in the fat field-effect transistor ͑FATFET͒ having a negligible ratio of the ungated surface to the total area between the source and the drain. This provides evidence that the hole-like trap peaks in the DLTS spectra originated from surface states at the ungated Al 0.24 Ga 0.76 As regions exposed between gate and source/drain electrodes. The activation energies for both surface states were determined to be 0.50Ϯ0.03 and 0.81Ϯ0.01 eV. The comparison of activation energies of the two surface states with the Schottky barrier height 0.66Ϯ0.01 eV suggests that H1 and H2 are deeply related to the Fermi energy pinning levels at the Al 0.24 Ga 0.76 As surface.

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“…It does not apply in other situations, e.g. to Al-containing compounds (84), where impurities are likely to occur at the interface. The proposal has been useful in suggesting means to increase barrier heights (85).…”

Section: Electrical Propertiesmentioning

confidence: 99%