Large-area wafer processing for 0.78-μm AlGaAs laser diodes

Large-area wafer processing for buried-ridge loss-guided inner-stripe AlGaAs laser diodes (LD's) has been developed for the first time. High uniformity of ridge waveguides on a 3-in wafer is realized by introducing selective wet etching. The standard deviations of the ridge width and the remaining p-cladding layer thickness on either side of the ridge, which have a great influence on the device characteristics, are 0.07 μm and 0.01 μm, respectively. As a result, good uniformity of laser characteristics has been obtained, for example, the distribution of full width at half maximum angles of far-field pattern in the direction parallel to the junction plane (/spl theta//sub ///) is only 0.22/spl deg/ (1/spl sigma/) for 1000 chips across a 3-in wafer.