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HL: Fachverband Halbleiterphysik

HL 30: Si/Ge

HL 30.4: Talk

Wednesday, March 25, 2009, 10:15–10:30, POT 51

Electronic and transport properties of semiconducting nanoparticles — •Andreas Gondorf¹, Martin Geller¹, Daniel Tadych¹, Axel Lorke¹, Cedrik Meier², and Hartmut Wiggers³ — ¹Experimental Physics and CeNIDE, University of Duisburg-Essen, Duisburg — ²Department of Physics, University of Paderborn — ³Combustion and Gas Dynamics, University of Duisburg-Essen

We investigate the charge carrier concentration and mobility in Ge and Si nanoparticle pellets. These transport properties are crucial for future Si or Ge based optoelectronic devices, as they determine the conductivity, for instance, in printable electronics. We use current-voltage (I-V) and Hall-measurements and find a very weak but measurable Hall-effect in compressed powder pellets. In pellets based on Si nanoparticles a very low charge carrier concentration of about 10¹² cm⁻³ is measured at 250^∘C while Ge nanoparticles show at 25^∘C two order of magnitude higher concentration of about 4·10¹⁴ cm⁻³. These numbers are comparable to the intrinsic charge carrier concentration in the corresponding bulk materials. Ge nanoparticles have a very small mobility of 0,1 cm²/Vs at 25^∘C which is comparable to the mobility of organic semiconductors. Surprisingly for Si nanoparticles we find mobilities of up to 100 cm²/Vs at 250^∘C which is not understood yet. Furthermore we show a simulation of I-V characteristics of semiconducting nanoparticles embedded in a dielectric matrix. The model includes the size dependent band gap and capacitance and the size distribution of the particles. The simulation is in good agreement with experimental results [C. H. Cho et al. Appl. Phys. Lett. 89 013116 (2006)].