Precise determination of polarization fields in c-plane GaN/Al x Ga1-x N/GaN heterostructures with capacitance–voltage-measurements

Norman Susilo, Marcel Schilling, Michael Narodovitch, Hsin-Hung Yao, Xiaohang Li, Bernd Witzigmann, Johannes Enslin, Martin Guttmann, Georgios G. Roumeliotis, Monir Rychetsky, Ingrid Koslow, Tim Wernicke, Tore Niermann, Michael Lehmann, Michael Kneissl

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Due to changes in the spontaneous and piezoelectric polarization, AlGaN/GaN heterostructures exhibit strong polarization fields at heterointerfaces. 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 this paper the polarization fields of thin AlGaN layers in a GaN matrix were determined by evaluating the changes in the depletion region width in comparison to a reference sample without heterostructure using capacitance–voltage-measurements. The polarization fields for Al0.09Ga0.91N (0.6 ± 0.7 MV cm−1), Al0.26Ga0.74N (2.3 ± 0.6 MV cm−1), Al0.34Ga0.66N (3.1 ± 0.6 MV cm−1), Al0.41Ga0.59N (4.0 ± 0.7 MV cm−1) and Al0.47Ga0.53N (5.0 ± 0.8 MV cm−1) heterostructures were determined. The results of the field strength and field direction of all samples are in excellent agreement with values predicted by theory and a capacitance–voltage based Poisson-carrier transport simulation approach giving experimental evidence for a nonlinear increasing polarization field with Al-concentration.
Original languageEnglish (US)
Pages (from-to)SCCB08
JournalJapanese Journal of Applied Physics
Volume58
Issue numberSC
DOIs
StatePublished - Apr 23 2019

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