Ridge waveguide AlGaAs heterostructure laser for single mode operation

In this paper, we provide results on a ridge-waveguide large optical cavity structure for single-mode operation. It requires only planar epitaxial growth and a single self-aligned etch step for current restriction and optical confinement. Five layers were grown on an n-GaAs:Si substrate by liquid phase epitaxy (LPE) in a confined graphite boat. The base structure consists of n-GaAs:Te (t mu m),n-Al/sub 0.4/GA/sub 0.6/As:Sn(2 mu m), undoped GaAs (0.1-0.3 mu m) active later, p-Al/sub 0.4/Ga/sub 0.6)As :Ge (1.5 mu m), and p-GaAs:Ge(1.5 mu m). After growth, the water is Zn diffused to form a p/sup +/ - GaAs contacting layer, and the n-GaAs substrate is lapped to a thickness of approx. 100 mu m. For N metallization, Au/Ge/Ni is evaporated and alloyed. On the p side; 8 mu m-wide stripes are defined by photolithography, and the p layers are etched in (011) direction by H/sub 3/PO/sub 4/:H/sub 2/O/sub 2/:H/sub 2/O (1:1:8) within 0.3 mu m of the active layer to form a 6 mu m-wide rid waveguide. The stripes were covered by second mask and the p-side were coated by an insulator material such as AlN.Cr-Au is then deposited and alloyed for the p-side metallization. The output/current characteristics was linear and stable fundamental lateral-mode operation was achieved with low threshold (< 100 MA) current. (author)