Step and Terrace Formation on Ge(111) Surface in H$_{2}$ Annealing

Nishimura, Tomonori; Lee, Choong Hyun; Nagashio, Kosuke; Toriumi, Akira

doi:10.1143/apex.5.121301

Cited by 17 publications

(24 citation statements)

References 20 publications

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“…This means that the control of the surface microroughness on a Ge surface is critically important. Apart from some pioneering works based on thermal processes, the surface flattening of Ge relies on conventional polishing, such as chemical mechanical polishing (CMP). We propose a novel process for flattening a Ge surface by catalyst‐assisted chemical etching.…”

Section: Figurementioning

confidence: 99%

“…[1] Although high-performance Ge-based metal-oxide semiconductor (MOS) transistors have been reported, [2][3][4] the obtained electron effective mobility is still not satisfactory.T his is probably caused by scattering at the oxide/Gei nterface, owing to its roughness. This means that the control of the surface microroughness on aG e surfacei sc ritically important.A part from some pioneering works based on thermalp rocesses, [5,6] the surfacef lattening of Ge relies on conventional polishing, such as chemical mechanical polishing (CMP). We propose an ovel process for flattening aG es urface by catalyst-assisted chemical etching.…”

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confidence: 99%

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Catalyst‐Assisted Electroless Flattening of Ge Surfaces in Dissolved‐O₂‐Containing Water

et al. 2015

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Control of the microroughness of Ge surfaces is required to realize field‐effect transistors with high performances. We propose a novel surface‐flattening process for Ge that involves the preferential transformation of surface protrusions on Ge into soluble GeO2 with the help of a catalyst in water. To carry out this process, we developed a setup comprising a catalyst plate covered with a Pt film in contact with a Ge surface in saturated O2‐dissolved water. The role of the metallic film is to enhance the oxygen reduction reaction in water that accompanies the oxidation of protrusions or microbumps on a Ge surface. After presenting the fundamental etching properties of a Ge surface treated with this metal‐assisted chemical etching method, we demonstrate that our water‐based process creates a flattened Ge surface that has few protrusions with a lateral size on the order of 10 nm.

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Section: Figurementioning

confidence: 99%

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confidence: 99%

Catalyst‐Assisted Electroless Flattening of Ge Surfaces in Dissolved‐O₂‐Containing Water

et al. 2015

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“…We found recently that atomically flat Ge(111) surface was achieved by 100% H 2 annealing at a relatively low temperature [6]. The RMS roughness of Ge(111) surface as a function of H 2 annealing time at 500 o C was shown in Fig.…”

Section: A Atomically Flat Ge/geo 2 Interface Formationmentioning

confidence: 87%

(Invited) Significant Enhancement of High-N_s Electron Mobility in Ge n-MOSFETs with Atomically Flat Ge/GeO₂ Interface

Lee

Nishimura

et al. 2014

ECS Trans.

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The rapid degradation of high-Ns electron mobility in Ge n-MOSFETs is still one of the greatest concerns in Ge CMOS technology. Although there are many possible origins so far considered, the degradation mechanism is still unclear in spite of its importance. In this work, we clarify wafer-related origins for electron mobility degradation in Ge n-MOSFETs. High-Ns electron mobility is dramatically improved thanks to (i) atomically flat Ge surface formation, followed by (ii) layer-by-layer oxidation. (iii) Oxygen-related neutral impurities in Ge substrates could be another origin of the mobility reduction on Ge wafers. By successfully eliminating these scattering sources in Ge n-MOSFETs, we demonstrate intrinsically high electron mobility in a wide range of Ns .

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“…2 (a). Thanks to the step and terrace structure formation, µm-range roughness is drastically improved (11). Furthermore, Fig.…”

Section: Surface Structure and Morphologymentioning

confidence: 91%

Atomically Flat Germanium (111) Surface by Hydrogen Annealing

Nishimura¹,

Kabuyanagi²,

Lee³

et al. 2013

ECS Trans.

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In germanium (Ge) MOSFET technology, surface planarization is a serious concern for mobility enhancement at high carrier density, reliability improvement of gate dielectrics and morphology control for non-planar FETs. In this work, (111)-oriented Ge substrates were annealed at 350-750oC in pure H2 atmosphere, and the surface structure and morphology were analyzed with atomic force microscopy. A step and terrace structure was observed on the surface after the H2 annealing above 500oC. The terrace width is controllable by the off-angle of the initial surface within 0.3o at least. The roughness root mean square (RMS) at 100 x 100 nm on single terrace is ~0.05 nm which is almost our detection limit, which implies that the single terrace on H2 annealed Ge (111) is atomically flat. Furthermore, even though the initial surface roughness RMS is intentionally increased up to 0.6 nm, atomically flat terrace structure could be obtained by the H2 annealing.

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Step and Terrace Formation on Ge(111) Surface in H$_{2}$ Annealing

Cited by 17 publications

References 20 publications

Catalyst‐Assisted Electroless Flattening of Ge Surfaces in Dissolved‐O₂‐Containing Water

Catalyst‐Assisted Electroless Flattening of Ge Surfaces in Dissolved‐O₂‐Containing Water

(Invited) Significant Enhancement of High-N_s Electron Mobility in Ge n-MOSFETs with Atomically Flat Ge/GeO₂ Interface

Atomically Flat Germanium (111) Surface by Hydrogen Annealing

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Step and Terrace Formation on Ge(111) Surface in H$_{2}$ Annealing

Cited by 17 publications

References 20 publications

Catalyst‐Assisted Electroless Flattening of Ge Surfaces in Dissolved‐O2‐Containing Water

Catalyst‐Assisted Electroless Flattening of Ge Surfaces in Dissolved‐O2‐Containing Water

(Invited) Significant Enhancement of High-Ns Electron Mobility in Ge n-MOSFETs with Atomically Flat Ge/GeO2 Interface

Atomically Flat Germanium (111) Surface by Hydrogen Annealing

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Product

Resources

About

Catalyst‐Assisted Electroless Flattening of Ge Surfaces in Dissolved‐O₂‐Containing Water

Catalyst‐Assisted Electroless Flattening of Ge Surfaces in Dissolved‐O₂‐Containing Water

(Invited) Significant Enhancement of High-N_s Electron Mobility in Ge n-MOSFETs with Atomically Flat Ge/GeO₂ Interface