C-V characteristics of ion implanted depletion IGFETs and buried channel CCDs

Capacitance voltage measurements of ion implanted devices for several circuit connections are presented and interpreted in terms of a simple constant profile approximation. Based on this model the device capacitance is described quantitatively in terms of the series combination of a p?n junction capacitance and a conventional MOS capacitance. It is shown that shallow and deep implants reveal characteristically distinctive C-V curves which provide an immediate rough estimate of the implant depth. Analysis of the model yields directly, important parameters for first order design purposes. It is also shown that the measurements provide a simple diagnostic technique to examine the physics of the implanted structure. The use of the simplified model is justified by the agreement between experimental and calculated values.