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HL: Fachverband Halbleiterphysik

HL 33: Poster Session III

HL 33.7: Poster

Mittwoch, 14. März 2018, 17:30–19:30, Poster F

Determination of polarization fields in group III-nitride heterostructures by capacitance-voltage measurements — •Marcel Schilling, Norman Susilo, Luca Sulmoni, Martin Guttmann, Tim Wernicke, and Michael Kneissl — Technische Universität Berlin, Institute of Solid State Physics, Hardenbergstraße 36, 10623 Berlin, Germany

Due to changes in the spontaneous and piezoelectric polarization, group III-nitride heterostructures exhibit strong polarization fields at heterointerfaces in the order of MV/cm. For quantum wells, the polarization fields lead to a strong band bending and a redshift of the emission wavelength, known as quantum-confined Stark effect. In order to study the influence of polarization fields in group III-nitride-based semiconductor devices, an accurate determination of the magnitude and direction of the polarization fields is of great importance.

We demonstrate a new method to precisely determine the polarization fields in group III-nitride heterostructures based on capacitance-voltage measurements. By evaluating the changes in the depletion region width of a pin diode or Schottky diode, we are able to determine the polarization fields with high accuracy. For this approach, it is necessary to compare the depletion region width of a reference sample without the heterostructure (i.e. homojunction) to a sample with a quantum well structure. Finally, we will discuss the accuracy and possible sources of errors for this method.