GaAs cleaning with a hydrogen radical beam gun in an ultrahigh-vacuum system

Sugata, Sumio

doi:10.1116/1.584302

Cited by 87 publications

(9 citation statements)

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“…(5) In combination with (2), this reaction seems to favor the formation of ZnTe patches on the sample surface, however, a continuous ZnTe coverage caused by exhausting the Cd in a complete layer on top of the CdZnTe substrate does not seem to take place during exposure times of a few 10 min as applied in this study. Hence, the roughening found for the etching of CdZnTe at higher temperature is attributed to patches of ZnTe which are partially resistant against the H 2 plasma etching at the expense of the CdTe component of the underlying CdZnTe.…”

Section: Temperature Effectsmentioning

confidence: 73%

Surface cleaning and etching of CdZnTe and CdTe in H2/Ar, CH4/H2/Ar, and CH4/H2/N2/Ar electron cyclotron resonance plasmas

Keller

Zimmermann

Seelmann‐Eggebert

et al. 1997

Journal of Elec Materi

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This paper compares H2/Ar, CH4/H2/Ar and CH4/H2/N2/Ar plasma etch processes for CdZnTe and CdTe substrates in view of their potential to provide high-quality substrate surfaces for subsequent HgCdTe epitaxy. An electron cyclotron resonance source was used as plasma generator, and ellipsometry, angle-resolved x-ray photoelectron spectroscopy and low energy electron diffraction were applied to characterize roughness, composition, and order of the resulting substrate surfaces. It was found that CdZnTe is much more susceptible to evolving surface roughness under H2/Ar plasma exposure than CdTe. The severe roughening observed at 100 deg C sample temperature was found to be correlated with a build-up of ZnTe at the surface, which suggests that the roughness formation may result from a preferential etching of the CdTe component. This surface degradation could be reduced by the addition of CH4, to the process gases. However, only a further addition of nitrogen gas balanced and substantially im proved the plasma process so that atomically clean, very smooth, and stoichiometrically composed CdZnTe surfaces of long-range order were eventually obtained

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Section: Temperature Effectsmentioning

confidence: 73%

Surface cleaning and etching of CdZnTe and CdTe in H2/Ar, CH4/H2/Ar, and CH4/H2/N2/Ar electron cyclotron resonance plasmas

Keller

Zimmermann

Seelmann‐Eggebert

et al. 1997

Journal of Elec Materi

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“…Until recently, the study of AH cleaning processes on epi-ready semiconductor substrates have been mostly based on diffraction and/or spectroscopic analysis techniques [3,8,10,11], with only a relatively limited amount of evidence obtained using atomic resolution methods such as scanning tunnelling microscopy (STM) [3,7]. In this paper, we present our studies of the effects of AH exposure on the surface morphology and structure of epi-ready GaAs(0 0 1), GaAs(1 1 0) and GaAs(1 1 1)A substrates by reflection highenergy electron diffraction (RHEED) and STM.…”

Section: Introductionmentioning

confidence: 99%

“…Atomic hydrogen (AH) cleaning has been shown in a number of studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14] to be a viable alternative method for the preparation of clean, atomically flat surfaces on a variety of III-V semiconductor substrates. The technique has several advantages over conventional thermal cleaning-much lower temperatures (p400 1C) are required; impurities (in particular oxide residues) are removed more rapidly and selectively; the procedure can be performed under UHV conditions; and the presence of a group V source is not required.…”

Section: Introductionmentioning

confidence: 99%

Atomic hydrogen cleaning of low-index GaAs surfaces

Khatiri

Krzyzewski

McConville

et al. 2005

Journal of Crystal Growth

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“…Previous reports showed that these experimental conditions for the atomic H cleaning on GaAs produce an atomically clean surface free of oxides. [12][13][14] The RHEED pattern was captured at 30 kV with an incident angle of 1 − 2°. The XPS data were recorded at intermediate steps in the sample preparation process using an Al K␣ 1 monochromatic source and a hemispherical analyzer.…”

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confidence: 99%

Indium stability on InGaAs during atomic H surface cleaning

Aguirre-Tostado

Milojević

Hinkle

et al. 2008

Applied Physics Letters

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Atomic H exposure of a GaAs surface at 390°C is a relatively simple method for removing the native oxides without altering the surface stoichiometry. In-situ reflection high energy electron diffraction and angle-resolved x-ray photoelectron spectroscopy have been used to show that this procedure applied to In 0.2 Ga 0.8 As effectively removes the native oxides resulting in an atomically clean surface. However, the bulk InGaAs stoichiometry is not preserved from this treatment. The In:Ga ratio from the substrate is found to decrease by 33%. The implications for high-mobility channel applications are discussed as the carrier mobility increases nearly linearly with the In content. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2919047͔One of the approaches being considered for future complementary metal-oxide-semiconductor devices is the substitution of silicon with high-mobility channels, where In x Ga 1−x As is one of the preferred candidates for metaloxide-semiconductor field-effect transistor ͑MOSFET͒ applications. 1 However, the interface thermal stability and interface quality of oxide insulators on InGaAs and other III-V semiconductors are far more complex than those on Si. Having more than one substrate element reacting with the oxide at the interface with different formation and decomposition energetics will lead to reaction channels resulting in various desorption and segregation products. 2 To preserve a stoichiometric InGaAs surface, one of the reported solutions employs an As-capping layer that is desorbed at relatively low temperatures 3,4 prior to further deposition. However, some methods for epitaxial growth of InGaAs on GaAs such as metal-organic chemical vapor deposition are not feasible with As capping. 5 An alternative to As capping includes passivation using the surface oxides which can be removed upon hydrogen plasma treatment ͑HPT͒ at a substrate temperature below 250°C, where it has been reported that no detectable surface decomposition occurs by x-ray photoelectron spectroscopy ͑XPS͒. 3,5 Atomic hydrogen treatment ͑AHT͒ from a H 2 thermal cracking source is an alternative technique for the removal of the oxide capping layer being advantageous over HPT as no H ions are supplied. This letter describes the reaction channels observed during the removal of air exposed grown native oxide on ͑13.5 nm͒ In 0.2 Ga 0.8 As/ GaAs͑001͒ upon AHT at 390°C and subsequent in-situ reflection high energy electron diffraction ͑RHEED͒ and XPS analysis. It is found that the AHT procedure results in an atomically clean ͑2 ϫ 4 reconstructed͒ In x Ga 1−x As surface. However, an indium depletion at the surface and subsurface regions is detected which may be expected to impact performance such as interface defect state densities and channel mobility in MOSFET devices. 6,7 The sample employed for this study was a commercial ͑13.5 nm͒ In 0.2 Ga 0.8 As layer grown by molecular beam epitaxy 8 on a semi-insulating GaAs͑001͒ wafer with a GaAs buffer layer of 535 nm thick. The In 0.2 Ga 0.8 As layer and GaAs buffer la...

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GaAs cleaning with a hydrogen radical beam gun in an ultrahigh-vacuum system

Cited by 87 publications

References 0 publications

Surface cleaning and etching of CdZnTe and CdTe in H2/Ar, CH4/H2/Ar, and CH4/H2/N2/Ar electron cyclotron resonance plasmas

Surface cleaning and etching of CdZnTe and CdTe in H2/Ar, CH4/H2/Ar, and CH4/H2/N2/Ar electron cyclotron resonance plasmas

Atomic hydrogen cleaning of low-index GaAs surfaces

Indium stability on InGaAs during atomic H surface cleaning

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