Piezoelectric and thermal effects on optical properties of violet-blue InGaN lasers

The optical properties of the violet-blue InGaN quantum-well lasers with an emission wavelength of 400-480 nm are studied with a LASTIP simulation program. Assuming that the InxGa1-xN/InyGa1-yN heterostructure has a band-offset ratio of 7/3, our simulation results indicate that the use of an AlGaN blocking layer can help reduce the electronic current overflow, and the non-uniform carrier distribution in the quantum wells plays an important role in the laser performance. If the piezoelectric effect is taken into account, the lowest threshold current of the violet-blue InGaN quantum-well lasers is obtained when the number of InGaN well layers is two if the emission wavelength is shorter than 412 nm, and one if the emission wavelength is longer than 412 nm. At a laser wavelength of 478 nm, the slope efficiency of the InGaN single quantum-well laser is decreased by ~2.4% and that of the double quantum-well laser is decreased by ~13.9% when the thermal effect is taken into account.