Electro–optic properties of InGaAs/GaAs quantum wires with V-shaped profile

Abstract

We have investigated the electro–optic properties of V-shaped InGaAs/GaAs quantum wires grown by MOCVD on patterned GaAs substrates. Two basic nanostructures have been fabricated: (i) single quantum wires and (ii) vertically stacked wires with different thickness of the barriers. The former exhibit a strong polarization anisotropy between the ground and the first excited states. The vertically stacked wires exhibit the formation of symmetric and antisymmetric states and a strong vertical coupling of the wavefunctions for narrow barrier widths. Based on these prototype structures we have fabricated an electro–optic modulator in wave-guide which exhibits a strong quantum confined Stark effect at room temperature, with bias as low as −2 V. The multiple wire stack has been used for the fabrication of a p–i–n quantum wire light emitter with the unprecedentedly low current threshold of 0.3 mA/cm 2 at low temperature.