Regensburg 2013 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 68: Poster Session: GaN: devices & preparation & characterization; III-V semiconductors; Photonic crystals; Semiconductor lasers

HL 68.6: Poster

Mittwoch, 13. März 2013, 16:00–20:00, Poster A

Light trapping in Gallium Nitride nanostructures formed by maskless dry etching — •Anna Haab, Jiehong Jin, Toma Stoica, Beata Kardynal, Andreas Winden, Hilde Hardtdegen, Martin Mikulics, and Detlev Grützmacher — Peter Grünberg Institut (PGI-9), Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich, 52425 Jülich, Germany

III-N alloys have attracted much attention as a candidate material system for solar cells, as their band gap can be tuned to cover the solar spectrum. For this application light management is of crucial importance and so patterning is used to reduce surface reflection and therefore to increase efficiency of the photonic devices. In this presentation we show that the simple, maskless reactive ion etching process, using a Cl2/Ar plasma of MOVPE grown GaN layers, can be employed to form arrays of nanowires suitable for light extraction/trapping. Both density and morphology of nanowires (from straight to conical) can be tuned, by varying the inductively coupled plasma power. We performed optimization of procedure to maximize light extraction/trapping in the GaN. The wavelength dependence of absorption was obtained from total transmission and reflection measurements for all samples. Photoluminescence analysis was used to assess potential damage from the etching process. We find that the strongest reduction of reflection is achieved in a dense array of straight nanowires. In such a structure the absorption just above the band gap increased to almost 100%, while the defects did not play a significant role. In future such structures can be used either as an antireflective coating or as substrates for overgrowth.