Fabrication of CdZnSe/ZnSe quantum dots and quantum wires by electron beam lithography and wet chemical etching

Abstract

We have developed a versatile and low-damage technology to realize quantum dots and quantum wires based on CdxZn1−xSe/ZnSe heterostructures. Electron beam lithography was used for pattern definition. The pattern transfer into the semiconductor was performed by a wet etch process based on a K2Cr2O7:HBr:H2O solution. Preferential etching along crystallographic planes leads to well-defined sidewalls of the freestanding dot and wire structures. Dot sizes down to 28 nm and wire sizes down to 13 nm have been achieved. High photoluminescence efficiencies, even in the narrowest structures, allow the study of lateral confinement effects. We observe a size dependent blueshift of up to 20 meV in the photoluminescence emission spectrum of the narrowest nanostructures. The measured energy shifts can be modeled based on a rectangular lateral potential well and the measured sizes of the structures.