Fabrication and Yield of Large-Area Quantum-Well Modulators

Large-area InP-based multiple quantum-well modulators were grown by molecular beam epitaxy and fabricated for free-space optical communication. The 6times6 mm devices were fabricated as pixilated 6times6 element arrays of 1times1 mm each. Transmission contrast of 3 dB was obtained with 15-V bias. Reverse bias leakage was measured across the arrays to obtain yield information. Yield was determined to be 92% of pixels with less than 300 A leakage at 15 V. Thus, we conclude these devices may be manufactured to operate at a single wavelength, that is, temperature stabilized. However, yield decreased greatly at larger biases which are required to achieve greater shifts of the exciton and wider wavelength range, which translates into wider temperature range. Thus, with the semiconductor material used here, finer pixilation would be required, or defect count must be reduced, to operate without temperature stabilization.