Optical waveguide apparatus and method of fabrication thereof

A semiconductor device, comprising:

• a semiconductor substrate;
• a buried oxide layer disposed on the semiconductor substrate;
• a first p-type doped feature and a first n-type doped feature disposed on the buried oxide layer;
• a waveguide feature disposed over the buried oxide layer and between the first p-type doped feature and the first n-type doped feature, the waveguide feature comprising a lower portion and an upper portion disposed over the lower portion;
• a second p-type doped feature sandwiched between the lower portion of the waveguide feature and the first p-type doped feature;
• and
• a second n-type doped feature sandwiched between the lower portion of the waveguide feature and the first n-type doped feature,
• wherein a p-type dopant concentration in the first p-type doped feature is greater than a p-type dopant concentration in the second p-type doped feature,
• wherein an n-type dopant concentration in the first n-type doped feature is greater than an n-type dopant concentration in the second n-type doped feature.

A semiconductor structure, comprising:

• a semiconductor substrate;
• an oxide layer disposed on the semiconductor substrate;
• a first dielectric layer disposed on the oxide layer;
• a first doped silicon feature and a second doped silicon feature disposed in the first dielectric layer;
• a first metal contact feature disposed over the first doped silicon feature;
• a second metal contact feature disposed over the second doped silicon feature;
• a first waveguide feature disposed between the first doped silicon feature and the second doped silicon feature;
• a second dielectric layer disposed over the first dielectric layer and between the first metal contact feature and the second metal contact feature;
• a second waveguide feature disposed in the second dielectric layer and between the first metal contact feature and the second metal contact feature;
• a first silicide layer sandwiched between the first doped silicon feature and the first metal contact feature;
• and
• a second silicide layer sandwiched between the second doped silicon feature and the second metal contact feature.