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ABSTRACT: We report on a sintering step in producing ultra‐fine silver aerosol particles to serve as etch masks for semiconductor quantum‐dot structures. Our experiments found heating conditions that reshape the Ag particles, resulting in a spherical shape and very good size uniformities. Using this improved aerosol generation technology, we have dry etched InP columns with 24±5 nm diameter and with very good uniformity, with nearly every aerosol particle resulting in a column. Column arrays with a density as high as 3×10<sup>9</sup> cm<sup>-2</sup> could be produced.
Applied Physics Letters 07/1994; · 3.84 Impact Factor
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ABSTRACT: By the application of aerosol techniques for the deposition of well‐defined particles of silver in combination with methane‐based electron cyclotron resonance plasma etching, we have been able to fabricate nanometer sized columns of InP. Silver particles are produced via homogeneous nucleation out of silver vapor saturated nitrogen gas from a tube furnace at around 1100 °C and, after size selection, deposited on the surface of InP. Scanning electron microscope images show that equally sized particles of silver, with an effective diameter in the range 20–40 nm, can be generated and deposited on the semiconductor. In a dry etching process applied subsequently we transfer vertically the feature of the particles into the InP material underneath producing free‐standing columns of InP with diameters as small as 50 nm.
Applied Physics Letters 09/1992; · 3.84 Impact Factor
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ABSTRACT: A new approach has been taken for the fabrication of Quantum Dot materials to be used for physics as well as for opto-electronics applications. We used a generation technique of ultrafine aerosol Ag particles which are deposited onto the surface of GalnAs/InP quantum well structures grown by Metal Organic Vapor Phase Epitaxy (MOVPE). The particles, ranging in size between 30 and 40 nm, are subsequently used as an etching mask. The Ag aerosol produced by homogeneous nucleation and can have a mean diameter in the range 2 – 100 nm. After size-selection, monodisperse particles with a very narrow size distribution are deposited onto the semiconductor surface at a density of about 109 cm-2. Low energy CH4/H/Ar Electron Cyclotron Resonance (ECR) plasma etching results in the formation of free-standing InP columns 50 to 80 nm in diameter and 120 to 280 nm in height. Their size and stability were found to be dependent on the etching conditions and the diameter of the particles. Low-temperature cathodoluminescence (CL) was used to evaluate the quantum dot structures fabricated by this technique.
MRS Proceedings. 12/1991; 283.
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ABSTRACT: We report on aerosol particles formed by bubbling a carrier gas through bubblers in metalorganic vapor phase epitaxy (MOVPE). A triethylgallium bubbler was investigated in a MOVPE set-up regarding the generation of aerosol. We measured particle number concentrations with an ultrafine condensation particle counter, which can detect submicrometer aerosol particles larger than 3 nm in diameter. We found that a standard triethylgallium bubbler used in a conventional way produces aerosol particles. The number of particles is a function of the carrier gas flow through the bubbler and correlates with the number of bubbles. The aerosol size distributions were analyzed with a differential mobility particle sizer and found to range from 10 to 600 nm, with maxima between 150 and 200 nm. Size distribution as well as total number of aerosol particles depend on evaporation processes during transport in undersaturated gas flows. While the number of particles reaching the reactor is not negligible, the precursor is predominantly transported as gas molecules. Particles can in principle, though, reach the substrate and create defects on the surface.
Journal of Crystal Growth.
