P-i-n transit time silicon-on-insulator device

A method of forming a transit time device in a semiconductor layer overlying an insulator layer, comprising the steps of:

• masking the semiconductor layer to expose a first selected location of the semiconductor layer;
• doping the exposed first selected location to a first conductivity type;
• masking the semiconductor layer to expose a second selected location of the semiconductor layer, the first and second selected locations separated from one another by a distance;
• doping the exposed second selected location to a second conductivity type, so that a portion of the semiconductor layer remaining between the first and second doped selected locations corresponds to an intrinsic region;
• forming an isolation structure to surround the first and second doped selected locations and the intrinsic region;
• doping the intrinsic region to a lightly-doped doping concentration relative to the first and second doped selected locations;
• after the doping steps, forming an epitaxial layer over the semiconductor layer;
• removing selected portions of the epitaxial layer, leaving first and second sinker structures overlying and in contact with the first and second doped selected locations of the semiconductor layer;
• and
• doping the first and second sinker structures to the first and respectively, so that said first and second sinker structures become the first and second conductivity types, respectively,
• wherein said first conductivity types is opposite to said second conductivity type.