Doping effects in p- and n-type layers of 390-nm InGaN DQW lasers

Abstract

The performance characteristics of deep violet InGaN laser diodes (LDs) are theoretically studied with the effects of doping concentrations in p- and n-type layers. Comprehensive study on output performance characteristics such as output power, threshold current, slope efficiency, DQE, and optical intensity, as well as on several internal parameters such as quantum well (QW) carrier densities, electron and hole current densities of deep violet InGaN double quantum well (DQW) lasers, have been done. The simulation results indicate that output power of LD is increased by increasing doping concentration in both n- and p-type layers. it can be due to increased carrier current densities and consequently increased radiative recombination. The results also indicate decrease in slope efficiency and DQE with increasing doping concentration. This situation can be caused by increasing nonradiative recombinations, such as Auger recombination inside and outside the active region, current overflow from the active region, and optical losses. Increasing current overflow from the active region also causes an increase in threshold current. Using higher doping concentration in n-type layers results in increase in electron current density in the n-side and consequently, higher electron flow in the active region. It causes an increase in higher radiative recombination and a higher need for holes and consequently, a higher hole current density in p-type layers. As well as, optical intensity of LDs is increased by increasing the doping concentration.