Highly doped GaAs:Si by molecular beam epitaxy

Abstract

Highly doped (N⁺⁺) GaAs:Si with n up to 1.8×10¹⁹ cm⁻³ has been grown by molecular beam epitaxy at a ‘‘normal’’ growth rate of ∼0.8 m/h⁻¹. These layers have been studied by Raman spectroscopy, van der Pauw–Hall measurements, and capacitance‐voltage plotting. They show no appreciable surface accumulation or diffusion of donors into low‐doped layers grown on top of them, and thus should be suitable as buffer layers for n/N⁺ devices as well as aiding in the production of low resistivity ohmic contacts. Resistivity of these layers has a lower limit of 4.75×10⁻⁴ Ω cm occurring at about 1.2×10¹⁹ cm⁻³. The possibility of this being an intrinsic lower limit to the resistivity of GaAs is discussed.