Design and application of silicon unipolar transistors made by diffusion techniques

Silicon unipolar transistors have been designed and fabricated using a shallow channel diffusion into lightly doped substrate material. The main gate is formed by diffusion of impurities of opposite conductivity type into selected areas of the channel region. Conventional photo-resistoxide masking techniques are used for defining electrode dimensions. The transistors are characterized by a transconductance which decreases linearily with increasing gate voltage. Such a characteristic is desirable for mixers. A theoretical analysis shows that impurity profiles obtained by diffusion are a sufficient approximation for the ideal case. Electrical device characteristics and equivalent circuits will be outlined.