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On the origin of interface states at oxide/III-nitride heterojunction interfaces

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Title: On the origin of interface states at oxide/III-nitride heterojunction interfaces
Authors: Matys, M. Browse this author
Adamowicz, B. Browse this author
Domanowska, A. Browse this author
Michalewicz, A. Browse this author
Stoklas, R. Browse this author
Akazawa, M. Browse this author →KAKEN DB
Yatabe, Z. Browse this author
Hashizume, T. Browse this author →KAKEN DB
Issue Date: 14-Dec-2016
Publisher: American Institute of Physics (AIP)
Journal Title: Journal of Applied Physics
Volume: 120
Issue: 22
Start Page: 225305
Publisher DOI: 10.1063/1.4971409
Abstract: The energy spectrum of interface state density, D-it(E), was determined at oxide/III-N heterojunction interfaces in the entire band gap, using two complementary photo-electric methods: (i) photo-assisted capacitance-voltage technique for the states distributed near the midgap and the conduction band (CB) and (ii) light intensity dependent photo-capacitance method for the states close to the valence band (VB). In addition, the Auger electron spectroscopy profiling was applied for the characterization of chemical composition of the interface region with the emphasis on carbon impurities, which can be responsible for the interface state creation. The studies were performed for the AlGaN/GaN metal-insulator-semiconductor heterostructures (MISH) with Al2O3 and SiO2 dielectric films and AlxGa1-x layers with x varying from 0.15 to 0.4 as well as for an Al2O3/InAlN/GaN MISH structure. For all structures, it was found that: (i) D-it(E) is an U-shaped continuum increasing from the midgap towards the CB and VB edges and (ii) interface states near the VB exhibit donor-like character. Furthermore, D-it(E) for SiO2/AlxGa1-x/GaN structures increased with rising x. It was also revealed that carbon impurities are not present in the oxide/III-N interface region, which indicates that probably the interface states are not related to carbon, as previously reported. Finally, it was proven that the obtained D-it(E) spectrum can be well fitted using a formula predicted by the disorder induced gap state model. This is an indication that the interface states at oxide/III-N interfaces can originate from the structural disorder of the interfacial region. Furthermore, at the oxide/barrier interface we revealed the presence of the positive fixed charge (Q(F)) which is not related to D-it(E) and which almost compensates the negative polarization charge (Q(pol)(-)).
Rights: The following article appeared in Journal of Applied Physics 120, 225305 (2016) and may be found at
Type: article
Appears in Collections:量子集積エレクトロニクス研究センター (Research Center for Integrated Quantum Electronics) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: Maciej Franciszek Matys

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