GROWTH OF P-TYPE AND N-TYPE GAAS/(ALGA)AS DOUBLE BARRIER RESONANT TUNNELING DEVICES ON (311)A AND (111)B SUBSTRATE ORIENTATIONS

A series of n-type and p-type double barrier resonant tunneling structures grown by molecular-beam epitaxy on different GaAs surface orientations have been investigated. Under identical growth conditions, Si incorporates preferentially as a donor for growth on (N11)B and as an acceptor on (N11)A surfaces (N = 1,2,3). We report the observation of hole resonant tunneling through p-type Si-doped GaAs/AlAs double barrier structures on the (311) A GaAs surface. The high quality of the layers and interfaces allows us to observe six well-defined resonant peaks in the current-voltage characteristics. The positions of the resonances are compared with an envelope function calculation of the energies of the bound hole states in a (311)A GaAs quantum well. The (311)A plane has biaxial symmetry and, by using angle-resolved magnetotunneling spectroscopy, we are able to observe the pronounced anisotropy with respect to the crystalline axes of the confined hole states in the valence band quantum well. The I(V) curves for the (311)A orientation are compared with those of similar Be-doped structures grown on the (100)-oriented surface. We also report measurements on double barrier resonant tunneling devices based on n-GaAs/(AlGa)As with [Al] = 0.4 and grown on the (111) B GaAs surface.