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Design of near lattice-matched AlGaInN-barriers for highly-scalable GaN-based transistor structures

: Lim, T.; Aidam, R.; Kirste, L.; Waltereit, P.; Müller, S.; Ambacher, O.


Physica status solidi. C 7 (2010), No.7-8, pp.1958-1960
ISSN: 1610-1634
ISSN: 1610-1642
ISSN: 1862-6351
International Conference on Nitride Semiconductors (ICNS) <8, 2009, Jeju/Korea>
Journal Article, Conference Paper
Fraunhofer IAF ()
(AlGaIn)N; MBE; structure; morphology; electrical property; transistor

AlGaInN layers at compositions near lattice-matched to GaN have been grown by molecular beam epitaxy. X-ray diffraction and atomic force microscopy show singlephase quaternary layers with smooth morphology. Heterostructures with thin nearly strain-free AlGaInNbarriers exhibit high values for sheet electron density and mobility ranging up to 2.1×1013 cm-2 and 1240 cm2/Vs, respectively. The epitaxial design of the structures comprises a multi-layer spacer which enables a wider separation between channel and barrier compared to a single AlN interlayer and serves as a protection during growth. A series of wafers with varied composition in the barrier reveals that the electron mobility increases with Gacontent in AlGaInN as expected considering the miscibility of quaternary nitrides.