The current-voltage characteristics of weakly coupled /spl delta/-doped GaAs/Al/sub x/Ga/sub 1-x/As superlattices

The /spl delta/-doped GaAs/Al/sub x/Ga/sub 1-x/As superlattice samples are grown by molecular beam epitaxy. The current- voltage, l(V). characteristics of the samples are measured at 1.5 K. The I(V) curves show the current-plateaus corresponding to the formation of the low- and high-electric field domains due to the ground state resonance and the first excited state to ground state resonance, respectively, in the quantum well. In addition to the typical sawtooth-like current branches, a new small current peak is observed accompanying each sawtooth-like current branch in our samples. Possible origins of the additional peaks are discussed in terms of cross-domain boundary tunneling and phonon emissions.