Effects of gap states on scanning tunneling spectra observed on (110)- and (001)-oriented clean surfaces and ultrathin Si layer covered surfaces of GaAs prepared by molecular beam epitaxy

Hasegawa, Hideki; Negoro, Noboru; Kasai, Seiya; Ishikawa, Yasuhiko; Fujikuwa, Hajime

doi:10.1116/1.1303857

Cited by 26 publications

(18 citation statements)

References 24 publications

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“…The conductance gap anomaly in STS spectra was reported previously on GaAs (001) surfaces [1,[3][4][5]. In this study, it was found that this anomaly also takes place on AlGaAs and InGaAs surfaces.…”

Section: Discussionsupporting

confidence: 57%

“…As an alternative model, we have proposed recently a new model based on where highly localized charging of the surface states due to direct supply or removal of electrons by the STM tip changes locally the magnitude of the surface band bending, and causes the observed anomaly [4,5]. Here, we assumed that the occupancy of the surface states is dynamically determined by the tip Fermi level rather the semiconductor bulk Fermi level due to fast tunneling into surface states and slow thermal escape of electrons from surface states.…”

Section: Discussionmentioning

confidence: 99%

“…STS spectra on (001) GaAs surfaces showed anomalously large conductance gaps, but did not show surface states in the conductance gap regions as indicated by Feenstra et al [7,8]. To explain this, we proposed a novel model based on a tip-induced local surface state charging and pointed out the correlation between the surface state density and the rate of finding anomalous spectra [4,5].…”

Section: Introductionmentioning

confidence: 99%

“…However, only limited work has been done so far on technologically important (001) III-V compound semiconductor surfaces [1][2][3][4][5] as compared with many studies on vacuum cleaved (110) surfaces initiating from the work by Feenstra et al [6][7][8]. STS spectra on (001) GaAs surfaces showed anomalously large conductance gaps, but did not show surface states in the conductance gap regions as indicated by Feenstra et al [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…The novel proposed model [4,5] was further extended and applied to the explanation of the experimental results.…”

Section: Introductionmentioning

confidence: 99%

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Conductance gap anomaly in scanning tunneling spectra of MBE-Grown (0 0 1) surfaces of III–V compound semiconductors

Kasai

Negoro

Hasegawa

2001

Applied Surface Science

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A scanning-tunneling-spectroscopy (STS) study was performed on MBE-grown (001) surfaces of GaAs, Al 0.3 Ga 0.7 As and In 0.53 Ga 0.47 As in an ultrahigh vacuum (UHV) STS system to clarify microscopic behavior of surface states causing Fermi level pinning on these III-V compound semiconductor surfaces. On all the sample surfaces, there existed spots which showed anomalous STS spectra showing conductance gaps much larger than the energy gap of the material. The rates of finding such spots as well as the magnitudes of the anomalous conductance gap were strongly material-dependent, increasing in the order of InGaAs, GaAs and AlGaAs. Scanning tunneling microscope (STM) images under low-positive sample biases showed dark areas which gradually decreased with the increase of the positive sample bias, and correlated with the spatial variation of conductance gaps of the STS spectra. On the basis of a detailed computer simulation, the conductance gap anomaly is explained by a tip-induced local charging of surface states where the apparent gap width depends on surface state distribution shape and density. The result shows that an extremely high density of surface states exist on the AlGaAs surface, but not so much on the InGaAs surface with the GaAs surface in between.

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Section: Discussionsupporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The novel proposed model [4,5] was further extended and applied to the explanation of the experimental results.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Conductance gap anomaly in scanning tunneling spectra of MBE-Grown (0 0 1) surfaces of III–V compound semiconductors

Kasai

Negoro

Hasegawa

2001

Applied Surface Science

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Surface passivation of epitaxial multilayer structures for InP‐based high‐speed devices by an ultrathin silicon layer

Xie

Takahashi

et al. 2002

Electron Comm Jpn Pt II

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SUMMARYA novel method for surface passivation of epitaxial multilayer structures for InP-based high-speed devices by an ultrathin silicon interface control layer (Si ICL) is discussed. Theoretical design and optimization of the surface passivation structure with and without an InGaAs cap layer is performed by taking account of the strain effect and quantized states in the Si ICL. Then the formation process of a SiN x /Si ICL structure utilizing a novel partial-nitridation technique is optimized. It is clarified that the InGaAs cap layer is important for Si ICL-based surface passivation on the InP-based materials. Planar metal-insulator-semiconductor (MIS) diodes are studied to characterize the insulator-semiconductor (I-S) interface fabricated on semi-insulating InP substrates, also showing that the Si ICL method is useful for the surface passivation of InP-based multilayer structures.

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Large-Scale Integration of Quantum Dot Devices on MBE-Based Quantum Wire Networks

Nano Science and Technolgy

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Effects of gap states on scanning tunneling spectra observed on (110)- and (001)-oriented clean surfaces and ultrathin Si layer covered surfaces of GaAs prepared by molecular beam epitaxy

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Cited by 26 publications

References 24 publications

Conductance gap anomaly in scanning tunneling spectra of MBE-Grown (0 0 1) surfaces of III–V compound semiconductors

Conductance gap anomaly in scanning tunneling spectra of MBE-Grown (0 0 1) surfaces of III–V compound semiconductors

Surface passivation of epitaxial multilayer structures for InP‐based high‐speed devices by an ultrathin silicon layer

Large-Scale Integration of Quantum Dot Devices on MBE-Based Quantum Wire Networks

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