Multi-wavelength lasers fabricated by a novel impurity-free quantum well intermixing technology

Abstract

Using impurity free vacancy enhanced disordering (IFVD), the shift in the band gap of Al0.3Ga0.7As/GaAs QW structures can be precisely controlled by an Al layer buried between a spin-on silica film and wet-oxidized GaAs surface. The blue shift in wavelength of Al0.3Ga0.7As/GaAs QW photoluminescence (PL) depends linearly on the thickness of the buried Al layer. By changing the Al layer thickness, the PL peak wavelength can be tuned from 7870 angstrom for the as-grown sample to 7300 angstrom and 7050 angstrom after 20s and 45s rapid thermal annealing at 850°C respectively. Applying this technology, three wavelength lasers were successfully fabricated in a single chip. The laser is a GaAs/Al0.3Ga0.7As three quantum well GRIN-SCH structure. Al layers with different thickness, i.e., no Al, 200 angstrom and 300 angstrom thick respectively, were buried between the oxidized GaAs surface and the silica film by two step photo-lithography and lift-off in three adjacent regions with 200μm spacing. After one step rapid thermal annealing, the wafer was processed into 6μm oxide-stripe lasers. At room temperature the intermixed lasers covered with different thickness of Al layer show different lasing wavelengths. All the lasers have similar threshold current and slope efficiency.