Abstract

Strain-relaxed InAlGaAs/InGaAs MQW device arrays with an exciton absorption peak at 1.06 μm are reported. The array will be used in flip-chip bonded Si/GaAs smart pixels operating at the wavelength corresponding to the emission of diode pumped solid state Nd-YAG lasers. The MQW devices are designed for both electro-optic modulation and detection in the pixels, while the logic functions are implemented by Si CMOS circuits. MQW modulators operating below the GaAs band edge have been demonstrated with strained GaAs/InGaAs MQWs on GaAs substrates. However, the indium content required for operation at 1.06 μm is about 25%, which results in a 2% lattice mismatch between InGaAs and GaAs. In this work, MQW structures are constructed by lattice-matched InAlGaAs/InGaAs multi-layers of the same indium content in both quaternary and ternary materials. The misfit strain from GaAs substrate was accommodated by a compositionally step-graded InAlGaAs buffer with each 0.3 to 0.5 μm thick step representing a less than 10% change in the indium composition. The band gap of each InAlGaAs layer was adjusted to be the same as that of GaAs by controlling the aluminum content. The preliminary results show an electro-absorption of 2500/ cm at 1.06 μm with an applied field of 3 × 105 V/cm.

© 1992 Optical Society of America