Strain effect on electronic and optical properties of GaN/AlGaN quantum-well lasers

Abstract

In order to clarify the strain effect on the GaN‐based lasers and to give the important guideline on their device design, the subband structure and the optical gains of strained wurtzite GaN/AlGaN quantum wells are theoretically investigated on the basis of k⋅p theory. First‐principles band calculations are used for deriving the unknown physical parameters. It is found that neither compressive nor tensile biaxial strains in the c plane are so effective on the reduction of the threshold carrier density as conventional zinc‐blende lasers and that the uniaxial strain in the c plane is very useful for reducing it. The relation between the uniaxial strain’s direction and the optical polarization is also clarified. As a result, we suggest that the uniaxial strain in the c plane is one of the preferable approaches for the efficient improvement of the GaN‐based lasers performance.