Novel high mobility Ga0.51In0.49P/GaAs modulation-doped field-effect transistor structures grown using a gas source molecular beam epitaxy

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Abstract
A standard Ga0.51In0.49P/GaAs modulation‐doped field‐effect transistor (MODFET) structure and a novel Ga0.51In0.49P/GaAs MODFET structure where the Ga0.51In0.49P spacer layer was replaced by an undoped Al0.3Ga0.7As layer were grown using a gas source molecular beam epitaxy. The Hall mobility of the novel MODFET’s structures are 6600 and 36 400 cm2/V s at room temperature and 77 K, respectively, which are more than twice as high as that in the ordinary Ga0.51In0.49P/GaAs MODFETs structure. The mobility is attributed to better carrier confinement and smoother heterointerface. Furthermore, it is found that both ordinary and novel MODFET’s structures have small photo‐persistant conductivity effects at low temperatures and that the FETs made in these materials had no threshold voltage shift at low temperatures after illumination.