Effect of design variations on the threshold current density of AlxGa1−xAs separate confinement heterostructure single quantum well lasers

Abstract

Data from a series of separate confinement heterostructure quantum well AlxGa1−xAs lasers of various structural design are analyzed so as to define material and device parameters suitable for subsequent modeling and threshold current optimization of arbitrary separate confinement laser structures. By modeling variations in inner barrier and cladding layer compositions, inner barrier width, and quantum well size, we show that, through proper design, low threshold current densities can be realized for structures having both indirect and direct barriers, further demonstrating that electron confinement due to a separate confinement heterostructure has no effect on carrier collection in the quantum well active layer. We also demonstrate the insensitivity of threshold current density to deviations in barrier width from an optimum value due to simultaneously induced variations in the optical confinement factor and overall optical loss coefficient.