High‐current AlInN/GaN field effect transistors

Abstract

AbstractWe present a study on AlInN/GaN field effect transistors (FETs) grown by metalorganic chemical vapor phase epitaxy. AlInN can be grown lattice‐matched to GaN with an In concentration of 18%. In this study samples with In concentrations ranging from 9.5 to 24%, covering a range from tensely to compressively strained AlInN layers, were grown on GaN layers on Si(111). From Hall effect and capacitance‐voltage measurements we find high sheet carrier densities for most of the samples indicating a high electron density at the AlInN/GaN heterointerface. This is also reflected in the behavior of processed FETs. Nearly lattice‐matched structures show sheet carrier densities of 3.2 × 1013 cm–2 and mobilities up to ∼406 cm2/Vs. Such Al0.84In0.16N FETs have maximum DC currents of 1.33 A/mm for devices with 1 µm gate length and 100 µm gate width and an output power of 2.5 W/mm at 2 GHz. The best devices with In concentrations of 19% show maximum output powers of 4.1 W/mm at 2 GHz. In contrast to that a compressively strained AlInN layer with an In concentration of 24% leads to a decreased polarization charge at the heterointerface and a low DC current of ∼70 mA/mm. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)