Selectivity control of Stark-ladder transitions in asymmetric double-well GaAs/AlAs superlattices by barrier sequence modulation

We have investigated field-induced features of optical transitions in asymmetric double-well superlattices (ADW-SLs) with and without barrier sequence modulation by low-temperature photocurrent (PC) spectroscopy. The difference between the heavy-hole confinement energies in the wide and narrow wells results in two types of Stark-ladder transitions, so that four ±1st-order spatially indirect transitions are expected to exist in the ADW-SL. The oscillator strength of these indirect transitions is affected by the strength and the direction of coupling between the wide and narrow wells. The introduction of the barrier sequence modulation into the ADW-SL realizes the control of these coupling mechanisms. This technique is a new method to modulate the oscillator strength of the indirect Stark-ladder transitions.