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HL: Fachverband Halbleiterphysik
HL 35: Poster I
HL 35.51: Poster
Tuesday, March 8, 2016, 15:00–19:00, Poster A
Growth kinetics of GaP-nanowires employing TBP and TMGa — •Matthias Steidl, Christian Koppka, Peter Kleinschmidt, and Thomas Hannappel — TU Ilmenau, Institute of Physics, Department of Photovoltaics, Gustav-Kirchhoff-Str. 5, D-98693 Ilmenau, Germany
III-V nanowires (NWs) are promising candidates as components of future third generation photovoltaic devices and solar water splitting cells. Here, the moderately high band gap (Eg=2.3eV) and stability in many electrolytes makes GaP a suitable material. Moreover, by adding As or N the band gap can be tuned making the material highly interesting for tandem devices e.g. with silicon sub cells. While the growth kinetics of GaP and GaAs NWs using PH3 and AsH3 are already studied in detail, the growth kinetics of GaP NWs applying TBP have not been thoroughly investigated so far. Here, we report on the influence of V/III ratio, temperature and carrier gas on the Au-assisted VLS growth of GaP NWs by MOVPE. We found a great impact of the temperature on the growth behaviour. For low temperatures (450∘C) the NW length does not increase linear with time - the longer the NW the smaller its growth rate (GR). In contrast, above 475∘C, the GR is constant. The GR reaches its maximum at around 488∘C and decreases above. As no Arrhenius dependency can be derived, the growth kinetics in this parameter regime are not governed by only one rate determining step. Moreover, a linear dependency of the GR on the V/III ratio (=5-20) was found for 450∘C. Here, changing the carrier gas from pure H2 to a mixture of H2/N2 increases the GR by a factor of two.