Controlling the Positions of Energy Subbands in GaAs/AlGaAs Heterostructures over a Wide Range up to the Continuum

Abstract

We report an experimental investigation of a method for controlling the positions of energy subbands in a wide quantum well by introducing thin, tunnel-transparent barriers. Transmission electron microscopy and X-ray diffractometry measurements demonstrate the high epitaxial quality of the grown GaAs/AlGaAs heterostructures of various configurations, including those containing ultrathin layers (1–2 nm thick). Low-temperature photoluminescence measurements indicate a shift in exciton recombination energy toward higher energies as the number of introduced barriers increases. It is found that the experimental and theoretical energies of the lowest electron subband and the highest hole subband are in qualitative agreement and cover a wide range, extending from the bottom of the quantum wells up to the continuum.