Berlin 2024 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 1: Nitrides: Preparation and characterization I

HL 1.4: Vortrag

Montag, 18. März 2024, 10:15–10:30, EW 015

n-type doping of GaN via pulsed sputter epitaxy — •Florian Hörich, Jürgen Bläsing, Jona Grümbel, Martin Feneberg, Rüdiger Goldhahn, Armin Dadgar, and André Strittmatter — Otto-von-Guericke University

Semiconductor devices like HEMTs typically employ a highly insulating buffer and a current transport layer. Recent developments in reactive sputter epitaxy have led to high resistances and breakdown field strenghs for GaN /1/. This talk focusses on n-type doping of GaN via co-sputtering with Si and Ge. For both dopants carrier concentrations ranging from 10¹⁷ up to 10²⁰ cm^-3 are feasible. The carrier density evaluated by Hall-effect and by PL measurements, evaluated for the free-carrier concentration by the bandgap shift (Burstein-Moss effect) /2/, are in good agreement. Just like MOVPE grown layers, highly Si doped layers tend to surface roughening due to SiN formation. This effect is even more pronounced for Ge doped layers. The relatively low growth temperature of 750 ^∘C likely promotes GexNy formation. Contrary to MOVPE results, XRD measurements show an additional peak in the θ/2θ-Scan for Ge doped layers, indicating a distortion of the lattice.

/1/ A. Dadgar et al, Phys. Stat. Sol. a 220, 2200609 (2022) /2/ M. Feneberg et al. Physical Review B 90, 075203397 (2014)