Quantum pillar structures on n+ gallium arsenide fabricated using ‘‘natural’’ lithography

Abstract

Random arrays of CsCl hemispherically shaped islands with average diameters as small as 500 Å have been made on n+GaAs substrates. The CsCl behaves as a resist of high selectivity when the GaAs is reactively ion etched in a BCl3 plasma. The resulting structure is a set of pillars all the same height, but with varying diameters, typically ±15% of the average value, 〈D〉. Typical pillar packing density, S, is 20%. Photoluminescence (PL) studies were made at 10 K on n+ and semi-insulating GaAs using 514.5 nm exciting radiation. PL spectra from n+GaAs structures of 〈D〉=520±78 Å, h=800 Å, S=20%; 〈D〉=610±97 Å, h=450 Å, S=12%; 〈D〉=1215±210 Å, h=600 Å, S=20%, as well as a plane surface, are reported. There is a shift in the peak value of the PL curves with respect to the planar structure of 26, 13, and 2.5 meV, respectively. It may be possible to understand these shifts in terms of quantum confinement effects if the effective pillar size is reduced by surface space charge effects.

Resistance bi-stability in resonant tunneling diode pillar arrays

“…6 First, we evaporate a thin gold film onto the semiconductor surface. It is well documented that for film thicknesses less than around 10 nm, gold forms a granular layer composed of disconnected islands.…”

Fabrication of GaInAs quantum disks using self-organized InP islands as a mask in wet chemical etching

“…Typically, in these methods nanoscale particles are introduced to the surface. For example, polystyre spheres, 4 aerosol Ag particles, 5 CsCl islands, 6 and Au islands 7 have been employed. In addition, InAs islands grown in Stranski-Krastanow growth mode have been used as a mask in chloride gas etching.…”

Geometry Induced Localization of Electrons in Quantum Pillars

“…Their size ranges from 500 (width) 800 (height) in GaAs to 50/ (width) lain (height) in Si [2]. All of them have interesting optical properties with potential device applications [1], [3]. The Si pillars, in particular, exhibit visible luminescence at 620 rim, which is very similar to the one observed in porous Si, thus enhancing the view that this phenomenon is a quantum size effect and is not related to some surface defect or impurity complex [3], [4].…”

“…Quantum Pillars, i.e., arrays of nanometer boxes deposited on a substrate of the same material as the pillars, have been produced in the laboratory using both Si and GaAs [1], [2]. Their size ranges from 500 (width) 800 (height) in GaAs to 50/ (width) lain (height) in Si [2].…”