EVALUATION OF WAVE-FUNCTION COHERENCE LENGTH IN A WAVE-GUIDING STRUCTURE EMBEDDING A INGAAS INP SHORT-PERIOD SUPERLATTICE/

We have studied the coherence length of the electronic wavefunction in an InGaAs/InP superlattice structure prepared by chemical beam epitax y. The sample, a p-i-n structure, was processed to form a waveguide mo dulator, and transmittance and photocurrent measurements were taken at varying photon energy and bias. Clear spectral features were observed in the transmittance measurements that are related to the Wannier-Sta rk effect. The spectral structures bear information about the coherenc e length of the electronic wave-function, which was found to be about 45 nm at room temperature.