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HL: Fachverband Halbleiterphysik

HL 7: Poster I

HL 7.40: Poster

Monday, March 27, 2023, 13:00–15:00, P2/EG

Controlling the dimensions of top-down GaN nanowire ensembles via self-assembled metal islands — •Rose Mary Jose, Jingxuan Kang, Miriam Oliva, Thomas Auzelle, Abbes Tahraoui, Oliver Brandt, and Lutz Geelhaar — Paul-Drude-Institut für Festkörperelektronik, 10117 Berlin, Germany

The large surface-to-volume ratio of semiconductor nanowires and their potential for enhanced light absorption are attractive for photoelectrochemical applications. In this context, large-scale nanowire arrays are needed. For top-down fabrication, a scalable and rapid way to form a nano-island mask is the dewetting of a metal film.

In this work, we study how Pt films evolve upon thermal treatment into nano-islands which serve as a shadow mask for the top-down etching of GaN nanowire ensembles. To gain control over the nano-island ensembles' dimensions, we explore variations of the annealing conditions, Pt film thickness, and the surface energy by investigating Pt dewetting on GaN, SiNx, and SiOx surfaces. The islands' size and density are determined by the initial Pt film thickness. However, nano-island diameter and spacing are coupled by a fixed ratio. Therefore, individually controlling the spacing between nano-islands and their diameter is challenging in this approach.

Nanowire arrays are fabricated using Pt dewetting masks by plasma etching followed by KOH wet etching. The resulting nanowires' dimensions are consistent with those of the original nano-islands. In our experiments, diameters in the range 30 nm-200 nm and lengths of 500-1000 nm are demonstrated.