Simple technique for evaluating dimensional and compositional changes in selective-area-grown MQW laser diode

We report on a novel combination of measurement techniques for evaluating dimensional and compositional changes of selective-area-grown multiple-quantum-well laser diodes (SAG MQW LDs). This technique is based on C-V and I-V measurements of the fully fabricated LDs. Using this technique, the changes in the capacitance and voltage correspond to the layer thickness and bandgap energy. To verify the effectiveness of the proposed technique, we first fabricated an LD array containing ten different SAG MQW structures, and examined the effects of the dimensional and compositional changes on the wavelength shift both theoretically and experimentally. From our examination, we found that a wavelength shift of 83 nm is obtained for an SAG mask pattern with an opening width of 100 μm, and that a cross point between both dimensional and compositional changes exists for this mask pattern. As the following step, the fabricated LD array was tested using the proposed technique, and the growth rate enhancement and bandgap energy were extracted from the measured C-V and I-V results. The extracted data for each array channel were compared with the simulation results, which were well-fitted from the photo-luminescence (PL) measurements. They both show good agreement with the simulation results.