Porous germanium multilayers

Rojas, Enrique Garralaga; Hensen, Jan; Carstensen, Jürgen; Föll, H.; Brendel, Rolf

doi:10.1002/pssc.201000130

Cited by 10 publications

(5 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Langa et al showed that PGe formation is always accompanied by a constant dissolution of the already-formed pores (4), (5). We have demonstrated the formation of single and multi-layers by electrochemical etching in highly concentrated HF-based electrolytes ( 9)- (11). The dissolution of the already-formed porous layer is avoided by alternating the etching bias from anodic to cathodic (9), thus allowing doubleand multi-layer formation.…”

Section: Introductionmentioning

confidence: 80%

Porous Germanium Layers by Electrochemical Etching for Layer Transfer Processes of High-Efficiency Multi-Junction Solar Cells

Rojas¹,

Hensen²,

Carstensen³

et al. 2011

ECS Trans.

View full text Add to dashboard Cite

We demonstrate reproducible formation of mesoporous germanium layers suitable for solar energy applications by electrochemical etching in highly concentrated electrolytes. For long anodization times or thick layer formation a porosity gradient is observed leading eventually to high porosity regions and cavity formation at the bottom of the porous layer. A 30 min annealing step at a temperature of 575 ºC in hydrogen atmosphere allows for reorganization and subsequent lift-off. The mean surface roughness increases from 0.31 nm for unprocessed Ge up to 7.85 nm for reorganized Ge as measured by atomic force microscopy. µ-Raman confocal spectroscopy analysis confirms that etching and annealing do not affect the crystalline structure.

show abstract

Section: Introductionmentioning

confidence: 80%

Porous Germanium Layers by Electrochemical Etching for Layer Transfer Processes of High-Efficiency Multi-Junction Solar Cells

Rojas¹,

Hensen²,

Carstensen³

et al. 2011

ECS Trans.

View full text Add to dashboard Cite

show abstract

“…Similar to silicon etching, almost all known methods of electrochemical etching of germanium are based on the use of hydrofluoric [14–16] and hydrochloric acids [17] or alkalis, [18] which make them environmentally incompatible. High toxicity and a corrosive nature of the reagents recalls for the replacement of these old technologies.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Etching of Germanium in Ionic Liquids without the Use of Toxic and Corrosive Reagents

et al. 2021

View full text Add to dashboard Cite

For the first time, the possibility of obtaining porous germanium from both single‐crystal and polycrystalline starting materials using environmentally friendly (in contrast to the commonly used HF and HCl) imidazolium ionic liquids (IL) was shown. It was demonstrated that pore formation depended significantly on the viscosity of the IL, on the etching current density and etching time, and on defects and imperfections of the substrate surface. By varying these parameters, the rates of two competing processes – formation and growth of pores and electropolishing – could be adjusted, consequently allowing germanium with a various structured surface, including a porous surface. In particular, using a more viscous IL (for example, [BMIM][PF6] versus [BMIM][BF4]) made it possible to reduce the rate of dissolution of the germanium dioxide surface layer; as a result, the formation and growth of pores became a dominant process. At the same time, the dissolution rate of the already formed porous layer (electropolishing) increased with the etching current density and the number of defects and imperfections of the germanium surface.

show abstract

“…The passivated pore walls provide an energy barrier to charge transfer and inhibit the dissolution of the already formed porous layer. The same method was found by Rojas et al to be effective at forming multilayered meso-pGe. However, the realized mesoporous layers were extremely thin (<1 μm), and not suitable for the study of their structural properties.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Nanostructured Mesoporous Germanium for Application in Laser Desorption Ionization Mass Spectrometry

Abdelmaksoud

Guinan

Voelcker

2017

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is a high-throughput analytical technique ideally suited for small-molecule detection from different bodily fluids (e.g., saliva, urine, and blood plasma). Many SALDI-MS substrates require complex fabrication processes and further surface modifications. Furthermore, some substrates show instability upon exposure to ambient conditions and need to be kept under special inert conditions. We have successfully optimized mesoporous germanium (meso-pGe) using bipolar electrochemical etching and efficiently applied meso-pGe as a SALDI-MS substrate for the detection of illicit drugs such as in the context of workplace, roadside, and antiaddictive drug compliance. Argon plasma treatment improved the meso-pGe efficiency as a SALDI-MS substrate and eliminated the need for surface functionalization. The resulting substrate showed a precise surface geometry tuning by altering the etching parameters, and an outstanding performance for illicit drug detection with a limit of detection in Milli-Q water of 1.7 ng/mL and in spiked saliva as low as 5.3 ng/mL for cocaine. The meso-pGe substrate had a demonstrated stability over 56 days stored in ambient conditions. This proof-of-principle study demonstrates that meso-pGe can be reproducibly fabricated and applied as an analytical SALDI-MS substrate which opens the door for further analytical and forensic high-throughput applications.

show abstract

Porous germanium multilayers

Cited by 10 publications

References 20 publications

Porous Germanium Layers by Electrochemical Etching for Layer Transfer Processes of High-Efficiency Multi-Junction Solar Cells

Porous Germanium Layers by Electrochemical Etching for Layer Transfer Processes of High-Efficiency Multi-Junction Solar Cells

Electrochemical Etching of Germanium in Ionic Liquids without the Use of Toxic and Corrosive Reagents

Fabrication of Nanostructured Mesoporous Germanium for Application in Laser Desorption Ionization Mass Spectrometry

Contact Info

Product

Resources

About