Atomically flat planarization of Ge(100), (110), and (111) surfaces in H<sub>2</sub>annealing

Nishimura, Tomonori; Kabuyanagi, Shoichi; Zhang, Wen Feng; Lee, Choong Hyun; Yajima, Takeaki; Nagashio, Kosuke; Toriumi, Akira

doi:10.7567/apex.7.051301

Cited by 15 publications

(18 citation statements)

References 25 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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Catalyst‐Assisted Electroless Flattening of Ge Surfaces in Dissolved‐O₂‐Containing Water

et al. 2015

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“…After native oxide was removed on Ge surfaces by thermal cleaning in a hydrogen atmosphere [(i) in Fig. 1(d)] [14], AsH 3 was supplied to replace the outermost Ge with As [(ii) in Fig. 1(d)].…”

Section: Introductionmentioning

confidence: 99%

“…2(b)], can be seen to have formed. Vertical hexagonal pillars appeared on the (111)B-like polar surfaces (more specifically, As-incorporated Ge 3+ surfaces[14]) of the openings. However, inclined NWs were formed on the (111)A-polar ones, and hillocks appeared due to the mixture of (111)B/A surfaces.…”

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confidence: 99%

Growth of InGaAs nanowires on Ge(111) by selective-area metal-organic vapor-phase epitaxy

Yoshida

Tomioka

Ishizaka

et al. 2017

Journal of Crystal Growth

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We report the growth of InGaAs nanowires (NWs) on Ge(111) substrates using selective-area metal-organic vapor-phase epitaxy (SA-MOVPE) for novel InGaAs/Ge hybrid complementary metal-oxide-semiconductor (CMOS) applications. Ge(111) substrates with periodic arrays of mask opening were prepared, and InGaAs was selectively grown on the opening region of Ge(111). A uniform array of InGaAs NWs with a diameter around 100 nm was successfully grown using appropriate preparation of the initial surfaces with an AsH 3 thermal treatment and flow-rate modulation epitaxy (FME). We found that optimizing partial pressure of AsH 3 and the number of FME cycles improved the yield of vertical InGaAs NWs. Line-scan profile analysis of energy dispersive X-ray (EDX) spectrometry showed that the In composition in the InGaAs NW was almost constant from the bottom to the top. Transmission electron microscope (TEM) analysis revealed that the interface between InGaAs NW and Ge had misfit dislocations, but their distance was longer than that expected from the difference in their lattice constants.

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“…On the other hand, much less research attention has been paid to the surface chemistry of H(g) on Ge(100) compared with Si(100) [15][16][17][18][19]. While germanium attracts renewed attention in view of the next-generation semiconductor technology due to its high carrier mobility [20][21][22][23][24][25][26][27][28][29][30], we decided to perform a comparative study on the H(g)/ Ge(100) system. Compared with c-Si, c-Ge has a larger lattice constant and a weaker Ge-Ge bond on average.…”

Section: Introductionmentioning

confidence: 99%

Surface Reactions of Atomic Hydrogen with Ge(100) in Comparison with Si(100)

2017

Appl. Sci. Converg. Technol.

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The reactions of thermal hydrogen atoms H(g) with the Ge(100) surface were examined with temperatureprogrammed desorption (TPD) mass spectrometry. Concomitant H 2 and CH 4 TPD spectra taken from the H(g)irradiated Ge(100) surface were distinctly different for low and high H(g) doses/substrate temperatures. Reactions suggested by our data are: (1) adsorbed mono(β 1)-/di-hydride(β 2)-H(a) formation; (2) H(a)-by-H(g) abstraction; (3) GeH 3 (a)-by-H(g) abstraction (Ge etching); and (4) hydrogenated amorphous germanium a-Ge:H formation. While all these reactions occur, albeit at higher temperatures, also on Si(100), H(g) absorption by Ge(100) was not detected. This is in contrast to Si(100) which absorbed H(g) readily once the surface roughened on the atomic scale. While this result is rather against expectation from its weaker and longer Ge-Ge bond as well as a larger lattice constant, we attribute the absence of direct H(g) absorption to insufficient atomic-scale surface roughening and to highly efficient subsurface hydrogenation at moderate (>300 K) and low (≤300 K) temperatures, respectively.

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Atomically flat planarization of Ge(100), (110), and (111) surfaces in H₂annealing

Cited by 15 publications

References 25 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

Growth of InGaAs nanowires on Ge(111) by selective-area metal-organic vapor-phase epitaxy

Surface Reactions of Atomic Hydrogen with Ge(100) in Comparison with Si(100)

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Atomically flat planarization of Ge(100), (110), and (111) surfaces in H2annealing

Cited by 15 publications

References 25 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

Growth of InGaAs nanowires on Ge(111) by selective-area metal-organic vapor-phase epitaxy

Surface Reactions of Atomic Hydrogen with Ge(100) in Comparison with Si(100)

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Atomically flat planarization of Ge(100), (110), and (111) surfaces in H₂annealing

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

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