RECOMBINATION VELOCITY AT OXIDE-GAAS INTERFACES FABRICATED BY IN-SITUMOLECULAR-BEAM EPITAXY

The recombination velocity at oxide-GaAs interfaces fabricated by in s itu multiple-chamber molecular beam epitaxy has been investigated. Ga2 O3, Al2O3, SiO2, and MgO films have been deposited on clean, atomicall y ordered n- and p-type (100) GaAs surfaces using molecular beams of G a-, Al-, Si-, and Mg oxide, respectively. Based on the internal quantu m efficiency measured for incident Light power densities 1 less than o r equal to P-0 less than or equal to 10(4) W/cm(2), the interface reco mbination velocity S has been inferred using a self-consistent numeric al heterostructure device model. While Al2O3-, SiO2- and MgO-GaAs stru ctures are characterized by an interface recombination velocity which is comparable to that of a bare GaAs surface (congruent to 10(7) cm/s) , S observed at Ga2O3-GaAs interfaces is as low as 4000-5000 cm/s. The excellent Ga2O3-GaAs interface recombination velocity is consistent w ith the previously reported low interface state density in the mid 10( 10) cm(-2) eV(-1) range. (C) 1996 American Institute of Physics.