Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 47: Quantum dots and wires: Optical properties II

HL 47.3: Vortrag

Freitag, 5. April 2019, 10:00–10:15, H34

Determination of doping profiles in axial GaAs Nanowires by 4-point-probe and Luminescence Measurements — Andreas Nägelein¹, •Peter Kleinschmidt¹, Cornelia Timm¹, Matthias Steidl¹, Klaus Schwarzburg², and Thomas Hannappel¹ — ¹TU Ilmenau, Institut für Physik, 98693 Ilmenau, Germany — ²Helmholtz-Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany

Semiconductor devices depend crucially on the controlled incorporation of dopants and their spatial distribution. In the case of III-V nanowires (NWs), a number of techniques have been developed to analyze this property, but precise, rapid and non-destructive doping profiling is still challenging. Here, we investigate axial pn-junctions in GaAs-NWs, on the one hand electrically by a multi-tip scanning tunneling microscope (MT-STM) operated as a four-point nanoprober and on the other hand optically by room-temperature photoluminescence (PL) and cathodoluminescence (CL) microscopy spectroscopy. We fabricate the NWs by metalorganic vapor phase epitaxy in the vapor liquid solid growth mode. The MT-STM is accessible via a contamination-free UHV transfer, while optical characterization is performed in ambient air. Both approaches provide complementary information on doping distribution. Analysis of the MT-STM measurements involves a transport model, whereas analyzing the PL and CL data relies on semi-empirical equations taking the Burstein-Moss shift and the bandgap narrowing into account. Combining these results reveals a constant hole concentration in the p-dope base of the NWs and an axial variation in the electron concentration in the n-doped top part of the NWs.