Formation of High Aspect Ratio GaAs Nanostructures with Metal-Assisted Chemical Etching

Abstract

Periodic high aspect ratio GaAs nanopillars with widths in the range of 500-1000 nm are produced by metal-assisted chemical etching (MacEtch) using n-type (100) GaAs substrates and Au catalyst films patterned with soft lithography. Depending on the etchant concentration and etching temperature, GaAs nanowires with either vertical or undulating sidewalls are formed with an etch rate of 1-2 μm/min. The realization of high aspect ratio III-V nanostructure arrays by wet etching can potentially transform the fabrication of a variety of optoelectronic device structures including distributed Bragg reflector (DBR) and distributed feedback (DFB) semiconductor lasers, where the surface grating is currently fabricated by dry etching.

Ultra-high aspect ratio high-resolution nanofabrication for hard X-ray diffractive optics

“…A thin Ti layer was also used, as an adhesion layer for the liftoff process, and later dissolved in the etchant solution. It is well known from the literature that other metal catalysts, such as Ag 28 and Pt 29 , as well as other substrates such as GaAs 30 , can be etched using this method. Therefore, this technique is not limited only to the specific catalyst material and substrate materials used here.…”

Metal-assisted chemical etching of Ge surface and its effect on photovoltaic devices

“…While extensive efforts involving MaCE have focused on Si, MaCE has also been used for the fabrication of GaAs nanowires [10], GaAs hole arrays [11] and GaN nanowires [12]. However, there has been a limited number of reports on MaCE of germanium [13][14][15], a carbon-group element that is chemically similar to silicon.…”

Metal-assisted chemical etching of GaAs using Au catalyst deposited on the backside of a substrate

“…After sputtering the Au thin films on the reverse sides of the substrates, the specimens with shapecontrolled resist patterns on their surfaces were immersed in a mixed solution of 5 mol dm À3 H 2 SO 4 and 0.07 mol dm À3 KMnO 4 at 35-45 C under ambient light. KMnO 4 acts as an oxidizing agent in an acidic solution [9,22].…”

“…When a resist line pattern with a width of 8 mm was used, the resist layer acted as an etching mask to allow the exposed region to be etched. shows the cross-sectional SEM image of (100) GaAs after chemical etching for 30 min in a mixed solution of 5 mol dm À3 H 2 SO 4 and 0.07 mol dm À3 KMnO 4 at 35 C. This acidified KMnO 4 solution was more appropriate for the metal-assisted chemical etching of GaAs than the HF-containing solution commonly used for the metalassisted chemical etching of silicon for the aforementioned reason [9,22]. Even when no metal catalyst was used, the exposed GaAs surface in the interspaces of the resist lines was selectively To investigate the effect of metal catalysts on the etching rate of GaAs substrates, Au thin films were deposited on the backsides of GaAs substrates.…”

“…Since then, it has been reported that metal-assisted chemical etching can be applied to not only silicon substrates [2][3][4][5] but also other III-V compound semiconductors such as GaAs [6][7][8][9][10] and InP [11][12][13]. For an overview of the metal-assisted chemical etching of silicon, refer to recent reports in the literature [14][15][16].…”