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DS: Fachverband Dünne Schichten

DS 16: Thermoelectric and Phase Change Materials; Layer Deposition

DS 16.4: Talk

Thursday, March 30, 2023, 12:15–12:30, SCH A 315

Self-assembled droplet etching during semiconductor epitaxy for versatile quantum structures — •Christian Heyn, Ahmed Alshaikh, and Robert Blick — Center for Hybrid Nanostructures (CHyN), University of Hamburg

As a fundamental extension of conventional epitaxy, we describe the integration of self-assembled top-down strategies into the bottom-up molecular beam epitaxy (MBE) of semiconductor quantum structures (QS). The samples are fabricated using standard solid-source MBE without any additional equipment. Ga, Al, or In droplets are formed on a GaAs or AlGaAs surface driven by the minimization of surface and interface energies in Volmer-Weber mode. The metal droplets drill self-assembled nanoholes into the semiconductor surface which is called local droplet etching (LDE). Afterwards, the nanoholes are filled with a material different from the substrate for the generation of QS. This presentation discusses the general mechanism of LDE, the influence of the process parameters on the density, size, and shape of the resulting nanoholes, as well as an intermixing with substrate material. For LDE with Ga droplets on AlGaAs, a crystalline wall formed around a nanohole represents a GaAs quantum ring. Further strain-free QS are created by filling of nanoholes drilled using Al droplets in AlGaAs with GaAs. The size and shape of the resulting QS is controlled by the initial nanohole, the amount of deposited material for hole filling, and capillary. Examples are QS that are shaped like the shell of a cone and vertically coupled quantum dot molecules.