Properties of nanometer-sized metal–semiconductor interfaces of GaAs and InP formed by an <i>in situ</i> electrochemical process

Hasegawa, Hideki; Sato, Taketomo; Kaneshiro, C.

doi:10.1116/1.590838

Cited by 38 publications

(34 citation statements)

References 14 publications

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“…The pulsed in-situ electrochemical process [44][45][46][47] consists of controlled anodic etching of semiconductors followed by subsequent cathodic deposition of metal in the same electrolyte including metal ions, using the waveforms show in Fig.7(a). Electrochemical deposition of Bi on GaAs was reported by Vereecken et al [48].…”

Section: Formation Of Macroscopic Ms Interfaces By Pulsed In-situ Elementioning

confidence: 99%

“…The pulsed in-situ electrochemical process has been formed suitable also for formation of nanometer scale Schottky (nano-Schottky) contacts [47,56] that are required for gate control of quantum devices. This is because this process can form contacts consisting of metal nanoparticles with nearly ideal MS interfaces that are free from interfacial oxides, and very accurate control of thickness is possible by controlling the numper of pulses.…”

Section: Formation Of Nanometer Scale Schottky Contactsmentioning

confidence: 99%

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Electrochemical processes for formation, processing and gate control of III–V semiconductor nanostructures

Hasegawa

Sato

2005

Electrochimica Acta

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This paper reviews recent efforts by authors' group to utilize electrochemical processes for formation, processing and gate control of III-V semiconductor nanostructures. Topics include precise photo anodic and pulsed anodic etching of InP, formation of arrays of <001>-oriented straight nanopores in n-type (001) InP by anodization and their possible applications, and macroscopic and nanometer-scale metal contact formation on GaAs, InP and GaN by a pulsed in-situ electrochemical process, which remarkably reduces Fermi level pinning. All the results indicate that electrochemical processes can achieve unique and important results which the conventional semiconductor technology cannot realize, anticipating their increased importance in future semiconductor nanotechnology and nanoelectronics. Key words:III-V semiconductors, anodic etching, nanopore, electrodeposition, Schottky barrier 1.IntroductionIt is widely recognized that artificial semiconductor nanostructures such as quantum wires (QWRs) and quantum dots(QDs) give rise to new rich functionalities to materials. They produce new quantum state spectra with novel state transitions and linear and non-linear quantum transport phenomena, and open up opportunities for novel quantum devices which control quantum-mechanical behavior of electrons and photons in various sophisticated ways.The standard approach for semiconductor nanostructure formation is to use fine crystal growth techniques such as molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE). To fabricate devices, various standard etching and metal deposition techniques are used together with standard lithography techniques. However, the electrochemical approaches, if it attains sufficiently high controllability at the nanometerscale, seems to be highly useful for nanostructure formation and processing. The expected advantages include: (1) process simplicity and versatility, (2) capability of self-organization, (3) low processing temperature, (4) low process induced damage, (5) precise electrical control and (6) low processing costs.Some well known examples are porous Si formation [1,2] and use of anodized alumina as nanostructure templates for formation of carbon nanotubes [3].The purpose of this paper is to review recent attempts by the authors' group at RCIQE, Hokkaido University, that have been carried out in order to investigate feasibility of utilizing electrochemical processes for nanometer-scale processing and nanostructure formation in III-V semiconductors. Topics discussed in this paper include controlled (1) anodic etching of InP,

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Section: Formation Of Macroscopic Ms Interfaces By Pulsed In-situ Elementioning

confidence: 99%

Section: Formation Of Nanometer Scale Schottky Contactsmentioning

confidence: 99%

Electrochemical processes for formation, processing and gate control of III–V semiconductor nanostructures

Hasegawa

Sato

2005

Electrochimica Acta

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“…Namely, Schottky barrier heights (SBHs) approached to Schottky limit as the size of the contact is reduced in the nanometer range 1) . As a result, a high SBH value of 0.86 eV was obtained for Pt/n-InP Schottky contacts which is 0.4 eV larger than the conventional value.…”

Section: Introductionmentioning

confidence: 99%

“…I-V measurements of each of individual nanometer-sized Schottky contacts formed on n-GaAs and n-InP substrates using the in situ electrochemical process [1][2][3][4][5] were carried out using an atomic force microscopy (AFM) system equipped with a conductive probe. Theoretical analysis of I-V and C-V characteristics were carried out on the three-dimensional (3D) potential distributions underneath the nanometer-sized Schottky contacts calculated using a successive over relaxation (SOR) method.…”

Section: Introductionmentioning

confidence: 99%

Current transport and capacitance–voltage characteristics of GaAs and InP nanometer-sized Schottky contacts formed by in situ electrochemical process

Sato

Kasai

Hasegawa

2001

Applied Surface Science

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The nanometer-sized Schottky contacts were successively fabricated on n-GaAs and n-InP substrates by the electrochemical process, and their electrical properties were characterized both experimentally and theoretically. From the detailed I-V measurements using a conductive AFM system, it was found that the current transport properties of the nanometer-sized Schottky contacts were strongly dependent on metal workfunction, however showed nonlinear log I-V characteristics with large n value in range of 1.2 -2.0 which can not be explained by 1D thermionic emission model. From the theoretical analysis using a computer simulation, it was found that this nonlinear characteristics can be explained by the 3D thermionic emission model with a due consideration of the environmental Fermi level pinning. Furthermore, the calculated C-V characteristics showed much smaller movements of the depletion layer with bias underneath the nano-Schottky contacts. These results strongly indicate the importance of controlling the environmental Fermi level pinning to improve the potential controllability of the nano-Schottky contacts.

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“…Scanning tunneling spectroscopy ͑STS͒ of metallic clusters on a semiconductor surface has been used to study small metal-semiconductor contacts. 1 In addition, experiments have been carried out in which the tip of a scanning tunneling microscope ͑STM͒ was used to contact a semiconductor surface 2,3 or a metallic cluster on a semiconductor surface 4 to form a small Schottky contact. Various deviations from the large-diode models were revealed, e.g., enhanced conductance, which was interpreted as a lower effective barrier.…”

mentioning

confidence: 99%

Enhanced tunneling across nanometer-scale metal–semiconductor interfaces

Smit

Rogge

Klapwijk

2002

Applied Physics Letters

115

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We have measured electrical transport across epitaxial, nanometer-sized metal-semiconductor interfaces by contacting CoSi 2 islands grown on Si͑111͒ with the tip of a scanning tunneling microscope. The conductance per unit area was found to increase with decreasing diode area. Indeed, the zero-bias conductance was found to be ϳ10 4 times larger than expected from downscaling a conventional diode. These observations are explained by a model, which predicts a narrower barrier for small diodes and, therefore, a greatly increased contribution of tunneling to the electrical transport. © 2002 American Institute of Physics. ͓DOI: 10.1063/1.1467980͔Electrical transport through metal-semiconductor interfaces has received tremendous interest in the past decades, both experimentally and theoretically. Nevertheless, an important shortcoming of existing models is the restriction to infinitely extending interfaces, so that all parameters vary only in the direction perpendicular to the surface. When the interface size enters the nanoscale regime, many of these models cease to apply. Only a few experiments addressing this topic have been reported. In none of them epitaxial interfaces were used. Scanning tunneling spectroscopy ͑STS͒ of metallic clusters on a semiconductor surface has been used to study small metal-semiconductor contacts. 1 In addition, experiments have been carried out in which the tip of a scanning tunneling microscope ͑STM͒ was used to contact a semiconductor surface 2,3 or a metallic cluster on a semiconductor surface 4 to form a small Schottky contact. Various deviations from the large-diode models were revealed, e.g., enhanced conductance, which was interpreted as a lower effective barrier. Besides the work that addresses a single small diode directly, measurements have been carried out on many small diodes in parallel. 5,6 In this letter, we present measurements of electrical transport through an epitaxial, nanometer-sized metalsemiconductor interface. We argue that the observations can be explained by a simple model for the Schottky barrier thickness in metal-semiconductor interfaces smaller than the free-carrier screening length ͑Debye length, L D ͒. Our model predicts an interface-size-dependent barrier thickness, leading to greatly enhanced tunneling in small Schottky diodes. The CoSi 2 /Si(111) interface used in our experiments is among the few metal-semiconductor interfaces of which reliable Schottky barrier height ͑SBH͒ values exist, mainly because it can be grown as a virtually perfect, abrupt, epitaxial interface. 7 The SBH in this system is 0.67 eV ͑for n-type Si͒ and has been measured with various techniques. 7-9 It is, therefore, a nearly ideal system to study electrical properties of metal-semiconductor interfaces and has been intensely used for that purpose. Both in our model and in the analysis of the measurements, the SBH will be considered as a given quantity, because of the well-determined character of the CoSi 2 /Si (111) interface. We do not expect that ultra-small-size effects as repor...

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Properties of nanometer-sized metal–semiconductor interfaces of GaAs and InP formed by an in situ electrochemical process

Cited by 38 publications

References 14 publications

Electrochemical processes for formation, processing and gate control of III–V semiconductor nanostructures

Electrochemical processes for formation, processing and gate control of III–V semiconductor nanostructures

Current transport and capacitance–voltage characteristics of GaAs and InP nanometer-sized Schottky contacts formed by in situ electrochemical process

Enhanced tunneling across nanometer-scale metal–semiconductor interfaces

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