Optical and electrical characteristics of GaAs/AlGaAs GRIN-SCH lasers grown selectively by MBE on SiO2-patterned substrate

A GaAs/AlGaAs graded-index seperate confinement heterostructure (GRIN-SCH) laser is demonstrated by single selective molecular beam epitaxial (MBE) growth on SiO2-patterned GaAs substrate. The laser has a threshold current of 50 mA and lases in single longitudinal mode with a side suppression ratio of 95. The far-field pattern is primarily single-lobed up to 4 times threshold. Electrical test patterns show that the polycrystalline GaAs grown on SiO2near the boundaries with the single crystal conducts 20% of the current. However, by making the width of contact opening smaller than the width of the single crystal, the polycrystalline GaAs can provide very effective lateral current confinement. Lasers grown along [011] have lower threshold current than those along [ ] because of less scattering loss of light.