Record-high minority carrier lifetimes exceeding 10 ns are reported for GaA
s grown on Si wafers using compositionally graded GeSi buffers coupled with
monolayer-scale control of the GaAs/Ge interface nucleation during molecul
ar beam epitaxy. The GaAs layers are free of anti-phase domain disorder, wi
th threading dislocation densities at or below 2 x 10(6) cm(-2) Secondary i
on mass spectroscopy (SIMS) reveals that crossdiffusion of Ga, As and Ge at
the GaAs/Ge interface formed on the graded buffers are below detection lim
its in the interface region. Test diodes yielded excellent I-V characterist
ics, matching those of GaAs diodes on Ge and GaAs wafers, indicating that t
o a first order, threading dislocations do not limit device performance. (C
) 2001 Elsevier Science B.V. All rights reserved.