“…Note that previous works that made use of continuous metal film as etching catalyst [33][34][35]53 could not identify the crystal plane dependent etching mechanism since gold diffusion to the active sites is inhibited by the catalyst film itself. 32,54 er, which is also responsible for the pronounced spectral oscillations with typical Fabry-Perot pattern 55 (orange line in Fig. 3a).…”
Large area surface microstructuring is commonly employed to suppress light reflection and enhance light absorption in silicon photovoltaic devices, photodetectors, and image sensors. To date, however, there are no simple means to control the surface roughness of III-V semiconductors by chemical processes similar to the metal-assisted chemical etching of black Si. Here, we demonstrate the anisotropic metal-assisted chemical etching of GaAs wafers exploiting the lower etching rate of the monoatomic Ga<111> and <311> planes. By studying the dependence of this process on different crystal orientations, we propose a qualitative reaction mechanism responsible for the self-limiting anisotropic etching and show that the reflectance of the roughened surface of black GaAs reduces up to ∼50 times compared to polished wafers, nearly doubling its absorption. This method provides a new, simple, and scalable way to enhance light absorption and power conversion efficiency of GaAs solar cells and photodetectors.
“…Note that previous works that made use of continuous metal film as etching catalyst [33][34][35]53 could not identify the crystal plane dependent etching mechanism since gold diffusion to the active sites is inhibited by the catalyst film itself. 32,54 er, which is also responsible for the pronounced spectral oscillations with typical Fabry-Perot pattern 55 (orange line in Fig. 3a).…”
Large area surface microstructuring is commonly employed to suppress light reflection and enhance light absorption in silicon photovoltaic devices, photodetectors, and image sensors. To date, however, there are no simple means to control the surface roughness of III-V semiconductors by chemical processes similar to the metal-assisted chemical etching of black Si. Here, we demonstrate the anisotropic metal-assisted chemical etching of GaAs wafers exploiting the lower etching rate of the monoatomic Ga<111> and <311> planes. By studying the dependence of this process on different crystal orientations, we propose a qualitative reaction mechanism responsible for the self-limiting anisotropic etching and show that the reflectance of the roughened surface of black GaAs reduces up to ∼50 times compared to polished wafers, nearly doubling its absorption. This method provides a new, simple, and scalable way to enhance light absorption and power conversion efficiency of GaAs solar cells and photodetectors.
“…The periodicities of the GaAs nanopillar arrays were approximately 100 nm, corresponding to those of the Au dot arrays used as catalyst and the pores of the porous alumina used as the initial mask. To our knowledge, the dimensions (e.g., periodicity) of the structures obtained on GaAs via metal-assisted chemical etching in this study are smaller than those reported for other GaAs structures [19–22]. Fig.…”
Section: Resultsmentioning
confidence: 65%
“…1 c). KMnO 4 acts as an oxidizing agent in an acidic solution [ 19 – 22 ]. The morphologies of the alumina mask, deposited Au layer, and etched GaAs substrate were evaluated by field-emission scanning electron microscopy (FE-SEM; JEOL JSM-6701F).…”
GaAs nanopillar arrays were successfully fabricated by metal-assisted chemical etching using Au nanodot arrays. The nanodot arrays were formed on substrates by vacuum deposition through a porous alumina mask with an ordered array of openings. By using an etchant with a high acid concentration and low oxidant concentration at a relatively low temperature, the area surrounding the Au/GaAs interface could be etched selectively. Under the optimum conditions, Au-capped GaAs nanopillar arrays were formed with an ordered periodicity of 100 nm and pillar heights of 50 nm.
“…However, this is a multistep process requiring the use of photolithography with colloidal crystal templating in the first pre-etching step. Fabrication of GaAs nanopillars by metal-assisted chemical etching (MacEtch) also requires lithographic methods for catalytic metal patterning [ 25 – 26 ]. Among non-lithographic methods based on electrochemical etching, to the best of our knowledge, there is only one report on the preparation of high-aspect-ratio vertically aligned GaAs nanowires with a diameter of about 200 nm and a length of 100 µm on GaAs(111)B wafers with a carrier concentration in the range of (1–2) × 10 18 cm −3 [ 27 ].…”
A comparative study of the anodization processes occurring at the GaAs(111)A and GaAs(111)B surfaces exposed to electrochemical etching in neutral NaCl and acidic HNO3 aqueous electrolytes is performed in galvanostatic and potentiostatic anodization modes. Anodization in NaCl electrolytes was found to result in the formation of porous structures with porosity controlled either by current under the galvanostatic anodization, or by the potential under the potentiostatic anodization. Possibilities to produce multilayer porous structures are demonstrated. At the same time, one-step anodization in a HNO3 electrolyte is shown to lead to the formation of GaAs triangular shape nanowires with high aspect ratio (400 nm in diameter and 100 µm in length). The new data are compared to those previously obtained through anodizing GaAs(100) wafers in alkaline KOH electrolyte. An IR photodetector based on the GaAs nanowires is demonstrated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
