Optical properties of tensile-strained barrier GaAsP/GaAs intermixed quantum well structure

Abstract

The tensile-strained barrier GaAsP/GaAs quantum well (QW) structures fabricated on GaAs substrate has a remarkable potential for novel properties of laser structures. In this structure, the GaAs QW layer is embedded with tensile-strained GaAsP barriers grown on GaAs substrates. Recent research has reported that the threshold current densities with tensile-strained barrier QW laser are comparable with GaAsP/AlGaAs tensile-strained well QWs. In the case of tensile-strained barrier GaAsP/GaAs QW, a small amount of light-hole (LH) and heavy-hole (HH) splitting is attainable within a large range of well width and P compositions. By a suitable choice of material and structure parameters, it is possible to cause the coincidence of energy levels of HH and LH resulting in polarization-independent operation devices. In order to shift the HH and LH energy levels, the concept of band-gap engineering is a useful tool to accept the particular devices operation. Basically, intermixing process is one of easy ways to achieve the modification of bandstructure. During the process the as-grown square-QW compositional profile is modified to a graded profile thereby altering the confinement profile and subband structure in the QW. In this paper, the optical properties of intermixed GaAs QW with tensile-strained GaAsP barriers are reported.