Regensburg 2013 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
HL: Fachverband Halbleiterphysik
HL 68: Poster Session: GaN: devices & preparation & characterization; III-V semiconductors; Photonic crystals; Semiconductor lasers
HL 68.12: Poster
Wednesday, March 13, 2013, 16:00–20:00, Poster A
Growth of AlN by pulsed and conventional MOVPE — •Hanno Kröncke, Timo Aschenbrenner, Stefan Figge, and Detlev Hommel — Universität Bremen, Institut für Festkörperphysik
Due to low accessibility of pure aluminium nitride substrates, AlN-templates are appropriate for the growth of optoelectronic device emitting in the UV spectral region and high power / frequency electronic devices.
We have grown metal polar AlN layers up to 2 µm thickness on c-plane sapphire either by conventional metal organic vapor phase epitaxy (MOVPE) at 1270 ∘C or in pulsed growth mode at 1050 ∘C. For both methods we investigated different concepts of nucleation and the influence of V/III ratio and atmospheric conditions. The layers are atomically flat, showing pits in a density lower than 1· 107 cm−2 and edge type dislocations in the density of 3· 1010 cm−2 (pulsed) and 5· 109 cm−2 (conventionally).
In contrast to other publications on pulsed growth, our growth rate (1µm/h) is much higher than 1 ML/cycle, requiring a different growth mode, which was investigated by in situ reflectivity measurements.
For conventionally grown samples we investigated the influence of the growth atmosphere on the growth rate and applied a simple model based on diffusion, viscosity and gas flow velocity. In general the best quality is obtained by low V/III ratio of 100, pure hydrogen atmosphere at 50 Torr at 1250 ∘C.