Advanced numerical simulation program was used to analyze the performance of GaN
based vertical cavity surface emitting laser (VCSEL) with single, double and triple
quantum well(s) as active region. It was found that numbers of quantum well (QW)
variation inside the active region is the most critical factor on the VCSEL performance.
The lowest threshold current and highest in both the slope efficiency and differential
quantum efficiency were observed when the well number is double (DQWs) at 415
nm VCSEL. This is ascribed to that for single quantum well (SQW), some of the gain
begin to escape before lasing is achieved while for triple quantum wells (TQWs) while
are separated by many thick barriers, then transport carriers between wells will be
inefficient. As a result, a non-uniform carrier distribution may result.