AlGaSb Buffer Layers for Sb-Based Transistors

InAs quantum wells can serve as the channel for high-electron-mobility transistors. Structures are typically grown on semi-insulating GaAs sub-strates with 1.5 lm to 3.0 lm buffer layers of AlSb and AlGaSb accommo-dating the lattice mismatch. We demonstrate that high electron mobility in the InAs (>20,000 cm2/V s at 300 K) and smooth surfaces can be achieved with Al0.8Ga0.2Sb buffer layers as thin as 600 nm, grown at rates of 1.5 monolayers/s to 2.0 monolayers/s. The use of thinner buffer layers reduces molecular beam epitaxial growth time and source consumption. The buffer layers also exhibit higher resistivity, which should reduce excess gate leakage current and improve device isolation. Key words: InAs, AlGaSb, high-electron-mobility transistor (HEMT), molecular beam epitaxy (MBE), field-effect transistor (FET), buffer laye