New design of upper waveguide with unintentionally doped InGaN layer for InGaN-based laser diode

The optical and electrical characteristics of one new laser structure have been theoretically investigated, in which an unintentionally doped InGaN layer (u-InGaN) located between the last quantum barrier and the electron blocking layer is designed as the upper waveguide (UWG). It is found that this unintentionally doped InGaN layer is benefitted to achieve a low threshold current and larger output power due to a good optical field distribution and effective blockage of electron leakage. Meanwhile, according to the systematically analysis on the influence of indium content, background concentration and layer thickness, 100 nm In0.02Ga0.98N UWG with 1 × 1017 cm−3 background concentration is suitable for the new laser structure.