In/sub 0.52/(Al/sub 0.9/Ga/sub 0.1/)/sub 0.48/As/In/sub 0.53/Ga/sub 0.4/$ d7As HEMTs on InP substrates

摘要

In this report, we try to improve the quality of the In/sub 0.52/Al/sub 0.48/As layer, by substituting 10% of Al atoms with Ga atoms, and forming a In/sub 0.52/(Al/sub 0.9/Ga/sub 0.1/)/sub 0.48/As quaternary (Q) layer. This quaternary InAlGaAs layer is used as the Schottky and buffer layers in HEMT structures. With the incorporation of Ga atoms, the alloy scattering can be eliminated due to the higher surface mobility of Ga atoms during MBE growth. This composition is chosen based on the consideration of maintaining a good Schottky gate performance, where a reasonably high bandgap Schottky layer is necessary. Since it is expected that this InAlGaAs Q-layer can improve the device duality, we particularly focus on reliability and sidegate testing for InAlGaAs Q-HEMTs. For comparison, the results obtained from the conventional InP-HEMTs are also included.