Electron beam source molecular beam epitaxial growth of analog graded AlxGa1−xAs ballistic transistors

A new method has been developed for the growth of graded band-gap AlxGa1−xAs alloys by molecular beam epitaxy which is based upon electron beam evaporation of the group III elements. The metal fluxes are measured and feedback controlled using a modulated ion gauge sensor. The system is computer controlled which allows precise programming of the Ga and Al evaporation rates. The large dynamic response of the metal sources enables growth of variable band-gap III-V alloys with arbitrary composition profiles. This new technique is demonstrated by synthesis of analog graded AlxGa1−xAs unipolar ballistic electron transistors.