Piezoelectric effects on many-body optical gain of zinc-blende and wurtzite GaN/AlGaN quantum-well lasers

Electronic and optical properties for (001)-, (111)-oriented zinc-blende (ZB), and (0001)-oriented wurtzite (WZ) structures are investigated taking into account the piezoelectric (PZ) effects. Self-consistent (SC) calculation of electronic structure is also considered within Hartree approximation. Using the SC model with the PZ field, we show that the many-body optical gain of (111)-oriented ZB and (0001)-oriented WZ quantum well (QW) lasers is reduced compared to results using the flat-band (FB) model. This is caused by the separation between the electron and hole wave functions in the presence of PZ electric field. However, when the optical gain is plotted as a function of the radiative current density Jrad, it is found that there is no significant difference between the results of the FB and SC models. We believe that this is due to the fact that the peak gain and the radiative recombination current are reduced simultaneously with increasing PZ field. For the same threshold gain level, the ZB and WZ quantum well structures are expected to have nearly the same threshold current density Jth within 10%.