Details
| Original language | English |
|---|---|
| Pages (from-to) | 1731-1733 |
| Number of pages | 3 |
| Journal | Physica Status Solidi (C) Current Topics in Solid State Physics |
| Volume | 8 |
| Issue number | 6 |
| Early online date | 22 Jun 2011 |
| Publication status | Published - Jun 2011 |
| Externally published | Yes |
Abstract
We present the reproducible fabrication of porous germanium (PGe) single- and multilayers. Mesoporous layers form on heavily doped 4" p-type Ge wafers by electrochemical etching in highly concentrated HF-based electrolytes with concentrations in a range of 30-50 wt.%. Direct PGe formation is accompanied by a constant dissolution of the already-formed porous layer at the electrolyte/PGe interface, hence yielding a thinner substrate after etching. This effect inhibits multilayer formation as the starting layer is etched while forming the second layer. We avoid dissolution of the porous layer by alternating the etching bias from anodic to cathodic. PGe formation occurs during anodic etching whereas the cathodic step passivates pore walls with H-atoms and avoids electropolishing. The passivation lasts a limited time depending on the etching current density and electrolyte concentration, necessitating a repetition of the cathodic step at suitable intervals. With optimized alternating bias mesoporous multilayer production is possible. We control the porosity of each single layer by varying the etching current density and the electrolyte.
Keywords
- Electrochemical etching, Mesoporous layers, Multilayers, Porous germanium
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Condensed Matter Physics
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In: Physica Status Solidi (C) Current Topics in Solid State Physics, Vol. 8, No. 6, 06.2011, p. 1731-1733.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Porous germanium multilayers
AU - Garralaga Rojas, Enrique
AU - Hensen, Jan
AU - Carstensen, Jürgen
AU - Föll, Helmut
AU - Brendel, Rolf
N1 - Funding Information: The authors thank Bianca Gehring from the ISFH for the technical assistance. The financial support of this work by the German Ministry for Economy and Technology under contract no. 50JR0641 is gratefully acknowledged. E. Gar-ralaga Rojas especially thanks the European Space Agency for the financial support of his work in the framework of the Net-working Partnering Initiative (contract no. 20250/06/NL/GLC).
PY - 2011/6
Y1 - 2011/6
N2 - We present the reproducible fabrication of porous germanium (PGe) single- and multilayers. Mesoporous layers form on heavily doped 4" p-type Ge wafers by electrochemical etching in highly concentrated HF-based electrolytes with concentrations in a range of 30-50 wt.%. Direct PGe formation is accompanied by a constant dissolution of the already-formed porous layer at the electrolyte/PGe interface, hence yielding a thinner substrate after etching. This effect inhibits multilayer formation as the starting layer is etched while forming the second layer. We avoid dissolution of the porous layer by alternating the etching bias from anodic to cathodic. PGe formation occurs during anodic etching whereas the cathodic step passivates pore walls with H-atoms and avoids electropolishing. The passivation lasts a limited time depending on the etching current density and electrolyte concentration, necessitating a repetition of the cathodic step at suitable intervals. With optimized alternating bias mesoporous multilayer production is possible. We control the porosity of each single layer by varying the etching current density and the electrolyte.
AB - We present the reproducible fabrication of porous germanium (PGe) single- and multilayers. Mesoporous layers form on heavily doped 4" p-type Ge wafers by electrochemical etching in highly concentrated HF-based electrolytes with concentrations in a range of 30-50 wt.%. Direct PGe formation is accompanied by a constant dissolution of the already-formed porous layer at the electrolyte/PGe interface, hence yielding a thinner substrate after etching. This effect inhibits multilayer formation as the starting layer is etched while forming the second layer. We avoid dissolution of the porous layer by alternating the etching bias from anodic to cathodic. PGe formation occurs during anodic etching whereas the cathodic step passivates pore walls with H-atoms and avoids electropolishing. The passivation lasts a limited time depending on the etching current density and electrolyte concentration, necessitating a repetition of the cathodic step at suitable intervals. With optimized alternating bias mesoporous multilayer production is possible. We control the porosity of each single layer by varying the etching current density and the electrolyte.
KW - Electrochemical etching
KW - Mesoporous layers
KW - Multilayers
KW - Porous germanium
UR - http://www.scopus.com/inward/record.url?scp=79959638286&partnerID=8YFLogxK
U2 - 10.1002/pssc.201000130
DO - 10.1002/pssc.201000130
M3 - Article
AN - SCOPUS:79959638286
VL - 8
SP - 1731
EP - 1733
JO - Physica Status Solidi (C) Current Topics in Solid State Physics
JF - Physica Status Solidi (C) Current Topics in Solid State Physics
SN - 1862-6351
IS - 6
ER -