OPTICAL DEVICE HAVING STAINED BURIED CHANNEL

摘要

An optical device with a strained buried channel is provided to guarantee a desired switching speed and an improved operation speed by increasing modulation efficiency while avoiding a light attenuation phenomenon. A gate insulation layer(120) is formed on a semiconductor substrate of a first conductivity type. A gate(122) of a second conductivity type opposite to the first conductivity type is formed on the gate insulation layer. A high-density impurity diffusion region(132,134) is formed under the gate in the semiconductor substrate, doped with first conductive impurities having a higher density than that of the semiconductor substrate. A strained buried channel region(140) is extended to a portion between the gate insulation layer and the semiconductor substrate to come in contact with the high-density impurity diffusion region, made of a semiconductor material having a different lattice constant from that of a material constituting the semiconductor substrate. A semiconductor cap layer(142) is formed between the gate insulation layer and the strained buried channel region. The first conductivity type can be a p-type, having compressive stress.