Measurements on depletion-mode field effect transistors and buried channel MOS capacitors for the characterization of bulk transfer charge-coupled devices

The properties of bulk transfer charge-coupled devices (BCCD's) may be characterized from measurements obtained using MOS capacitors and field effect transistors. Models are presented for the MOS capacitor and field effect transistor for the case where a shallow doped layer of polarity opposite to that of the substrate is incorporated between the oxide and the substrate. These models explain the observed frequency dependence of the capacitance-voltage ( C- V) characteristics of these devices. Techniques are presented for determining the impurity profile of the buried layer from the low frequency C- V measurements made on MOS transistors. The majority carrier mobilities in the buried layer and at the surface are measured for the BCCD's and compared to the surface minority carrier mobility measured for the surface channel CCD's. Generation lifetimes at the surface, in the buried layer and in the underlying substrate are determined from capacitance-time (pulse bias C- t) measurements and leakage current measurements of the MOS capacitors and transistors. Methods are demonstrated whereby the depth from the oxide interface of the potential minimum (depth of the buried channel) and its potential can be determined as a function of the various applied biases.