Possibility of improved frequency response from intermixed quantum-well devices

We have measured the carrier capture times into intermixed In0.15Ga0.85As/Al0.2Ga0.8As quantum wells using the photoluminescence up-conversion technique. We confirm that the carrier capture into intermixed quantum wells is significantly shorter than capture into similar but nonintermixed samples. Using below and above band-gap excitation we were able to separate the various components effecting the carrier capture into the quantum well. We show that the reduction in the carrier capture times is not related to the introduction of nonradiative centres but is the consequence of the change in the quantum well potential caused by intermixing. These results indicate that intermixed devices may have higher cut-off modulation frequency than similar but noninternnixed devices. (C) 2001 Academic Press.