Metamorphic growth of 1.25 – 1.29 µm InGaAs quantum well lasers by molecular beam epitaxy
Artikel i vetenskaplig tidskrift, 2007
We demonstrate 1.25–1.29 μm metamorphic laser diodes grown on GaAs by molecular beam epitaxy (MBE) using an alloy-graded buffer layer (GBL). Use of Be in the GBL is effective to reduce surface/interface roughness and improves optical quality. The RMS surface roughness of the optimized metamorphic laser is only two atomic monolayers for 1×1 μm2. Cross-sectional transmission electron microscopy (TEM) images confirm that most dislocations are blocked in the GBL. Ridge waveguide lasers with 4 μm wide ridge were fabricated and characterized. The average threshold current under the pulsed excitation is in 170–200 mA for a cavity length of 0.9–1.5 mm. This value can be further reduced to about 100 mA by high-reflectivity coating. Lasers can work in an ambient temperature up to at least 50 °C.