Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 29: GaN: Pr
äparation und Charakterisierung II

HL 29.2: Talk

Wednesday, March 26, 2003, 14:45–15:00, BEY/118

Defect Spectroscopy of AlGaN/GaN Single Barrier Structures — •Martin Hermann, Barbara Baur, Martin Eickhoff und Martin Stutzmann — Walter Schottky Institut, Am Coulombwall, 85748 Garching

For a good perfomance of HEMTs based on AlGaN/GaN heterostructures it is nescessary to grow high quality barriers. Defects can strongly influence the mobility of the channel electrons, e.g. via ionized impurity scattering.

We investigated the transport properties of AlGaN/GaN heterostructures as a function of AlGaN barrier thickness and aluminum content. To determine the defect density in the barrier we used spectral photoconductivity measurements and photothermal deflection spectroscopy. A comparison of both methods allows us to determine the influence of the 2DEG in the case of the photoconductivity measurement. In addition we studied the influence of the interface defects using parallel conductance analysis and compared coplanar contact geometry with vertical contact geometry on samples prepared by the laser liftoff technique.