Gas source MBE growth of 1.3 μm-InAsP/InGaAsP quantum wells GRINSCH laser showing low threshold current density and high output power

Abstract

We report the successful fabrication of the first gas source MBE grown InAsP/InGaAsP multiple-quantum well lasers with compositional linearly graded InGaAsP confinement layers. The optical quality of the InAsP/InGaAsP quantum wells are investigated by room temperature photoluminesence (PL) spectroscopy; Intense PL-signal with small FWHM is observed in structures containing three quantum wells indicating that our structures are of high optical quality. Nonlinear temperature-ramps are developed and applied to the gallium effusion cell in order to grow lattice-match compositional linearly graded InGaAsP confinement layers. X-ray rocking curves show that the lattice-mismatches of the graded InGaAsP confinement layers. X-ray rocking curves show that the lattice-mismatches of the graded InGaAsP layers are well below 1×10 −3. These results indicate that the control of material supply during growth of the InGaAsP layers is highly precise. Laser structures containing graded confinement layers and three quantum wells are grown and fabricated into broad-area laser diodes. Threshold current density of 160A cm −2 was obtained for 1.5 mm long lasers. This value is among the lowest ever achieved for 1.3 μm lasers grown by any kind of MBE process.