Aqueous Electrodeposition of Ge Monolayers

Liang, Xiaojing; Kim, Youn-Geun; Gebergziabiher, Daniel K.; Stickney, John L.

doi:10.1021/la902929j

Cited by 52 publications

(86 citation statements)

References 53 publications

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“…A similar behavior was observed by Stickney et al 12 by STM, though at acidic pH, and by CV investigations in a wide range of pH. We hypothesize therefore that peak c2 is associated with the three-electron reduction process from germanate GeO 3 2− ions (Ge 4+ ) to GeOH ad (Ge + ), which may adsorb on the electrode surface, as described by Eq.…”

Section: Resultssupporting

confidence: 85%

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The Induced Electrochemical Codeposition of Cu-Ge Alloy Films

Zhao

Mibus

et al. 2017

J. Electrochem. Soc.

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Various examples of induced codeposition have been over time reported in the literature and partly understood. In particular, Brenner discussed as early as 1963 in his book “Electrodeposition of alloys” evidence of the induced deposition of Germanium; attempts to understand such mechanism however are lacking. In this work, the electrochemical co-deposition of Cu-Ge thin films from an alkaline tartrate-complexing electrolyte was investigated by combined cyclic voltammetry and quartz crystal microbalance of the unitary and alloy electrolytes. Ge undergoes reduction from Ge4+ (GeO32−) to Ge1− (GeH) in a two-step process and forms a self-limiting deposit, the thickness of which is a function of the Ge ion concentration and pH. Cu2+ deposition is strongly inhibited by the presence of Ge species above −1.2 V Ag/AgCl, while at more negative potentials a signature of alloy codeposition is present, in parallel with hydrogen evolution. Oxygen deposition is significant when Ge is at or above 25 at%. Induced codeposition is rationalized in terms of the activation of the Ge-H bond by Cu, resulting possibly in the formation of adsorbed species containing H-Cu-Ge, whereby H is dissociated, resulting in alloy growth in parallel with formation of a significant amount of H2 gas.

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Section: Resultssupporting

confidence: 85%

“…Previous studies 12,13,15,16 hypothesized that in this potential range the adsorbed Ge hydroxide would be converted into Ge hydride, which could act as the precursor for the onset of hydrogen formation. 16 The conversion from a Ge hydroxide to Ge hydride (Eq.…”

Section: Resultsmentioning

confidence: 99%

The Induced Electrochemical Codeposition of Cu-Ge Alloy Films

Zhao

Mibus

et al. 2017

J. Electrochem. Soc.

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“…[51][52][53] Raman spectra of the resulting deposits 53 indicated the presences of amorphous Ge. However, one sample examined using micro-Raman spectroscopy, Figure 12, produced a number of spectra from a particular area which displayed a band near 290 cm −1 .…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Formation of Germanene: pH 4.5

Ledina

Bui

Liang

et al. 2017

J. Electrochem. Soc.

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Germanene is a single layer allotrope of Ge, with a honeycomb structure similar to graphene. This report concerns the electrochemical formation of germanene in a pH 4.5 solution. The studies were performed using in situ Electrochemical Scanning Tunneling Microscopy (EC-STM), voltammetry, coulometry, surface X-ray diffraction (SXRD) and Raman spectroscopy to study germanene electrodeposition on Au(111) terraces. The deposition of Ge is kinetically slow and stops after 2–3 monolayers. EC-STM revealed a honeycomb (HC) structure with a rhombic unit cell, 0.44 ± 0.02 nm on a side, very close to that predicted for germanene in the literature. Ideally the HC structure is a continuous sheet, with six Ge atoms around each hole. However, only small domains, surrounded by defects, of this structure were observed in this study. The small coherence length and multiple rotations domains made direct observation with surface X-ray diffraction difficult. Raman spectroscopy was used to investigate the multi-layer Ge deposits. A peak near 290 cm−1, predicted to correspond to germanene, was observed on one particular area of the sample, while the rest resembled amorphous germanium. Electrochemical studies of germanene showed limited stability when exposed to oxygen.

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“…Electrochemical methods were only used for the growth of CTS by electrodeposition of a metallic precursor and annealing (EDA), as shown by the works of Berg et al, Robert et al and Koike and co-workers [11][12][13]. It is not surprising that electrochemical processes have not yet been applied to the growth of germaniumcontaining precursors for CTGS solar cells, since hydrogen evolution has a low overpotential on germanium so that it cannot be efficiently electrodeposited from aqueous solutions [14]. A low hydrogen overpotential implies that gas evolution occurs extensively in parallel with the reduction of germanium(IV) and current efficiencies drop dramatically.…”

Section: Introductionmentioning

confidence: 99%

Electrodeposition of germanium-containing precursors for Cu2(Sn,Ge)S3 thin film solar cells

Malaquias

Lin

et al. 2017

Electrochimica Acta

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A B S T R A C TCu 2 (Sn,Ge)S 3 has recently emerged as an absorber layer for single junction thin film solar cells, already achieving power conversion efficiencies of up to 6.7%. Electrodeposition of metallic precursors and their subsequent annealing is an attractive synthesis method for such solar cell absorber layers, since it does not require vacuum conditions and little energy is consumed. The aqueous electrodeposition of metallic germanium based on current knowledge is limited to very thin layers, which do not provide the stoichiometric amount of material required for thick semiconductor layers. Therefore we introduce an electrodeposition method for the growth of germanium-containing precursors for Cu 2 (Sn,Ge)S 3 , using propylene-glycol-based electrolytes. These baths do not require additives, give rates of germanium electrodeposition higher than other plating baths and are cheap. The electrochemical behaviour of copper, tin and germanium in propylene glycol was studied and the corresponding deposits were characterised. Smooth and compact layers of each of the pure elements were deposited. Additionally, the co-electrodeposition of copper and germanium was studied as well and thin films containing the alloy Cu 3 Ge and metallic copper were obtained. A constant [Cu]/[Ge] ratio of around 3 was found over a wide potential range, with a higher plating efficiency than that of pure germanium. For these reasons, copper and germanium were incorporated into the precursor via the referred co-deposition method. After thermal annealing in the presence of elemental sulphur, the semiconductor Cu 2 (Sn,Ge)S 3 was successfully formed and it was incorporated in a working solar cell structure with efficiency of 0.7%

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Aqueous Electrodeposition of Ge Monolayers

Cited by 52 publications

References 53 publications

The Induced Electrochemical Codeposition of Cu-Ge Alloy Films

The Induced Electrochemical Codeposition of Cu-Ge Alloy Films

Electrochemical Formation of Germanene: pH 4.5

Electrodeposition of germanium-containing precursors for Cu2(Sn,Ge)S3 thin film solar cells

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