Formation of porous Ge using HF‐based electrolytes

Flamand, Giovanni; Poortmans, Jef; Dessein, Kristof

doi:10.1002/pssc.200461130

Cited by 26 publications

(13 citation statements)

References 4 publications

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“…The nature of the attack solution was selected starting from the work formerly completed on germanium substrates [2][3][4][5][6][7]. In our case, a hydrofluoric acid solution HF (1:5) diluted by ethanol was thus used [3][4][5].…”

Section: Methodsmentioning

confidence: 99%

“…The choice of the electrochemical anodization in order to realize porous structures is made because of the capacity of this chemical process to produce homogeneous porous layers. Moreover, this process allows the control and variation of the porosity and thickness of the porous layers [1][2][3][4]. During the electrochemical process, the flow of a constant current during a certain time gives rise to the attack of indepth germanium and the formation of a homogeneous layer of porous material.…”

Section: Methodsmentioning

confidence: 99%

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Study and characterization of porous germanium for radiometric measurements

Akkari

Benachour

Aouida

et al. 2009

Phys. Status Solidi (c)

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The aim of this article is to study and realize a new detector based on a porous germanium (pGe) photodiode to be used as a standard for radiometric measurement in the wavelength region between 800 nm and 1700 nm. We present the development and characterization of a porous structure realized on a single‐crystal substrate of p‐type germanium (Ga doped) and of crystallographic orientation (100). The obtained structure allows, on the one hand, to trap the incident radiation, and on the other hand, to minimize the fluctuations of the front‐face reflection coefficient of the photodiode. The first studies thus made show that it is possible to optimize, respectively, the electrical current density and the electrochemical operation time necessary for obtaining exploitable porous structures. The obtained results show that for 50 mA/cm2 and 5 min as operational parameters, we obtain a textured aspect of the porous samples that present a pyramidal form. The reflectivity study of the front surface shows a constant value of around 38% in a spectral range between 800 nm and 1700 nm approximately. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Study and characterization of porous germanium for radiometric measurements

Akkari

Benachour

Aouida

et al. 2009

Phys. Status Solidi (c)

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“…It has been particularly challenging to synthesize group IV materials, such as Si and Ge, primarily owing to their strong covalent bonding and the need for high temperatures to promote crystallization [11][12][13]. Anodization and electrochemical etching [3,[14][15][16][17][18], spark processing [19,20] and inductively coupled plasma chemical vapor deposition (ICPCVD) [2,21] have been used to prepare porous Ge films. It is still a challenge to produce porous, semiconducting and luminescent Ge films in a simple and robust way, allowing their subsequent processing and integration into working devices [1][2][3][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…Anodization and electrochemical etching [3,[14][15][16][17][18], spark processing [19,20] and inductively coupled plasma chemical vapor deposition (ICPCVD) [2,21] have been used to prepare porous Ge films. It is still a challenge to produce porous, semiconducting and luminescent Ge films in a simple and robust way, allowing their subsequent processing and integration into working devices [1][2][3][14][15][16][17][18][19][20]. The porous structure plays an important role in the visible PL emission of the indirect bandgap semiconductors, such as Si and Ge [4][5][6][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…It is still a challenge to produce porous, semiconducting and luminescent Ge films in a simple and robust way, allowing their subsequent processing and integration into working devices [1][2][3][14][15][16][17][18][19][20]. The porous structure plays an important role in the visible PL emission of the indirect bandgap semiconductors, such as Si and Ge [4][5][6][14][15][16][17][18][19][20]. Formation of porous structures likely enhances electrical resistivity and carrier scattering rate, hindering measurements of the transport properties; it also may decrease the adhesion between the film and substrate.…”

Section: Introductionmentioning

confidence: 99%

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Fabrication and characteristics of porous germanium films

Chen

Zhang

Zang

et al. 2009

Science and Technology of Advanced Materials

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Porous germanium films with good adhesion to the substrate were produced by annealing GeO 2 ceramic films in H 2 atmosphere. The reduction of GeO 2 started at the top of a film and resulted in a Ge layer with a highly porous surface. TEM and Raman measurements reveal small Ge crystallites at the top layer and a higher degree of crystallinity at the bottom part of the Ge film; visible photoluminescence was detected from the small crystallites. Porous Ge films exhibit high density of holes (10 20 cm −3 ) and a maximum of Hall mobility at ∼225 K. Their p-type conductivity is dominated by the defect scattering mechanism.

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Porous germanium multilayers

Rojas

Hensen

Carstensen

et al. 2011

Phys. Status Solidi C

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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 (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Formation of porous Ge using HF‐based electrolytes

Cited by 26 publications

References 4 publications

Study and characterization of porous germanium for radiometric measurements

Study and characterization of porous germanium for radiometric measurements

Fabrication and characteristics of porous germanium films

Porous germanium multilayers

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