Optimization of 670-nm strained quantum well laser diodes

There is increasing interest in the use of visible emitting Ga_xIn_1-xP/(Al _0.5Ga_0.5)_0.52In_0.48P quantum well lasers for optical interconnections using polymer waveguides and this calls for the optimization of device structure for operation at a specific wavelength and usually at an elevated temperature. We concentrate on the mechanisms by which compressive strain modifies the threshold current in a regime where well composition (x) (strain) and quantum well width are adjusted to maintain a transition wavelength of 670 nm. In our model we assume a parabolic band structure, which is a reasonable approximation in this case since strain enhanced splitting of the valence bands is large, and we include the effects of monolayer fluctuations in well width and carrier-carrier scattering (where we calculate an energy and carrier density dependent lifetime). Using our model we examine the relative merits of various well composition (x)/well width combinations.