Dresden 2020 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 68: Nitrides: Preparation and characterization II

HL 68.5: Vortrag

Donnerstag, 19. März 2020, 16:00–16:15, POT 112

Thermally activated spreading resistance of Si- and Ge-doped lattice matched GaN/InAlN periodic stacks — •Hartmut Witte1, Cleophace Seneza1, Prabha Sana2, Christoph Berger1, Armin Dadgar1, and André Strittmatter11Institute of Physics, Otto-von-Guericke-University Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany — 2Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Walter-Huelse-Strasse 1, 06120 Halle, Germany

Si- or Ge-doped lattice-matched GaN/InAlN periodic stack structures were grown by MOVPE for applications as photonic band gap layers in the n-type region of GaN blue laser structures. For electrical transport measurements, mesa structures were realized with ohmic contacts on the bottom and the top of the stack. Besides the sheet resistance, a spreading resistance is observed depending on the contact geometry. Both IV- and CV-characteristics show rectifying behavior at low free electron concentrations and strong ohmic behavior at high electron concentrations. Temperature-dependent Hall- effect measurements verify metallic conduction associated with degenerately doped semiconductors. Contact arrangements for which a higher spreading resistance is found show an opposite temperature dependence of the resistance in IV- measurements. A defect assisted current mechanism via extended defects or the GaN/InAlN interfaces could be presented and will be investigated using CV- and thermal admittance spectroscopy. Kelvin probe microscopy and conductive atomic force microscopy will be employed to analyze surface-related electrical conduction.

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