Prospects for truly blue ZnSe/Zn1−uMguSvSe1−v/Zn1−xMgxSy Se1−y semiconductor diode lasers

The electrical and optical operation of separate confinement heterostructure quantum-well lasers of ZnSe/Zn1−uMguSvSe1−v/Zn1−xMgxSy Se1−y (blue laser) and Zn0.8Cd0.2Se/ZnS0.06Se0.94/ Zn1−zMgzSuSe1−u (blue-green laser) was studied by numerical simulation. The physical model was based on the self-consistent solution of Poisson’s equation, the current continuity equation, the photon rate equation, and the scalar wave equation. The band structure of strained quantum well was calculated using k⋅p theory, and the gain model was based on the interband electron-hole pair recombination without including excitonic effects. Good agreement was obtained between the experimental and the calculated output characteristics of Zn0.8Cd0.2Se/ZnSe0.06Se0.94/ Zn1−zMgzSuSe1−u blue-green lasers over a wide temperature range from 85 to 394 K. Further extension of these calculations to the ZnSe/Zn1−uMguSvSe1−v/Zn1−xMgxSy Se1−y structures demonstrated a considerable increase in threshold current density of blue lasers, due to the insufficient level of doping in wide-band p-Zn1−xMgxSySe1−y cladding layers. This would likely impose more stringent conditions for realization of continuous blue laser emission compared to their blue-green laser counterparts.