Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 53: Nitrides: Preparation of nonpolar and semipolar orientations

HL 53.5: Vortrag

Dienstag, 1. April 2014, 15:00–15:15, POT 151

Determination of polarisation fields in group III-nitride heterostructures by capacitance-voltage-measurements — •Monir Rychetsky1, Ingrid Koslow1, Jens Rass1,2, Tim Wernicke1, Konrad Bellmann1, Veit Hoffmann2, and Michael Kneissl1,21Technische Universität Berlin, Institut für Festkörperphysik, Germany — 2Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin, Germany

InGaN/GaN heterostructures exhibit strong piezoelectric and spontanous polarisation fields and sheet charges resulting in band bending. This leads to a reduction in the radiative recombination rate in light-emitting diodes (LEDs) and a red shift in the emission wavelength, due to the quantum-confined Stark effect.

There are several methods by which the magnitude and orientation of these polarisation fields have been measured. However, no exact values for the polarisation fields in semipolar planes have been reported.

In this contribution we propose a new approach to determine polarisation fields by using capacitance-voltage measurements. The sheet charges at the heterointerface influence the charge distribution in a PIN (positive intrinsic negative) junction and therefore the depletion width and the capacitance. In order to improve the accuracy of the method we compare the depletion width of two PIN junctions, one with an embedded InGaN layer and therefore influenced by the internal polarisation fields and one without it. First results of an In0.08Ga0.92N quantum well on (0001) show an internal field strength in the range of 0.95 - 1.25 MV/cm in [0001] direction.

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