[en] In this paper, the influence of a 10-nm-thick silicondioxide layer, as a passivation or as a gate insulation, on the performance of heterojunction field-effect transistors (HFETs) and metal–oxide–semiconductor HFETs (MOSHFETs), based on an undoped AlGaN/GaN heterostructure on a SiC substrate, was investigated. Channel-conductivity results yield a nearly 50% increase of mobility in the MOSHFET samples compared to the unpassivated HFETs. This increase of the transport properties of the MOSHFET channel is confirmed by a similar 45% increase of the cutoff frequency, from 16.5 to 24 GHz. Hall measurements, however, show a 10% decrease of the mobility in the heterostructure with a SiO2 top layer. In this paper, the superior performance of the MOSHFET transistor, in contradiction to the Hall results, is attributed to the screening of the Coulomb scattering of the charged surface defects by the gate-metallization layer.
Disciplines :
Electrical & electronics engineering
Identifiers :
UNILU:UL-ARTICLE-2009-356
Author, co-author :
MARSO, Michel ; Institute of Thin Films and Interfaces (ISG1) and cni - Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany
Heidelberger, Gero; Institute of Thin Films and Interfaces (ISG1) and cni - Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany
Indlekofer, Klaus Michael; Institute of Thin Films and Interfaces (ISG1) and cni - Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany
Bernát, Juraj; Institute of Thin Films and Interfaces (ISG1) and cni - Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany
Fox, Alfred; Institute of Thin Films and Interfaces (ISG1) and cni - Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany
Kordoš, P.; Institute of Electrical Engineering, Slovak Academy of Sciences, SK-84104 Bratislava, Slovak Republic
Lüth, Hans; Institute of Thin Films and Interfaces (ISG1) and cni - Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany
Language :
English
Title :
Origin of Improved RF Performance of AlGaN/GaN MOSHFETs Compared to HFETs,
Publication date :
2006
Journal title :
IEEE Transactions on Electron Devices
ISSN :
0018-9383
Publisher :
Institute of Electrical and Electronics Engineers, New York