Design of an N-Channel Jfet on High-Resistitivity Silicon for Radiation-Dectors On-Chip Front-End Electronics

We report on the design of an n-channel Junction Field Effect Transistor (JFET) on fully-depleted, high-resistivity 5 kOhm cm, n-type silicon substrate, which is intended to be utilized as active device in the on-chip preamplifier of the silicon radiation detectors. Two-dimensional process and device simulations are employed to optimize the device doping profile. As well as to point out some important advantages of the proposed structure over possible alternative device designs. In particular, the adopted device, in which a p-type externally-contacted well isolates the active device from the high-resistivity substrate, presents higher output-resistance values than a device directly fabricated on the substrate. Moreover, it is not affected by a parasitic phenomenon, resulting in gate-current increase and noise-performance degradation, which, in contrast, characterizes a device with floating well