This letter presents studies of several simple integrated circuits—n-channel metal-oxide semiconductor inverters, five-stage ring oscillators, and differential amplifiers—formed on thin, bendable plastic substrates with printed ribbons of ultrathin single-crystalline silicon as the semiconductor. The inverters exhibit gains as high as 2.5, the ring oscillators operate with oscillation frequencies between 8 and 9MHz at low supply voltages (∼4V), and the differential amplifiers show good performance and voltage gains of 1.3 for 500mV input signals. The responses of these systems to bending-induced strains show that relatively moderate changes of individual transistors can be significant for the operation of circuits that incorporate many transistors.

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Metal semiconductor field effect transistors (MESFETs) have been fabricated using a silicon-on-insulator (SOI) CMOS process. The MESFETs make use of a TiSi 2 Schottky gate and display good depletion mode characteristics with a threshold voltage of 0 5 V. The drain current can also be controlled by a voltage applied to the substrate, which then behaves as a MOS back gate. The transistors have been irradiated with 50 keV X-rays to a total ionizing dose in excess of 1 Mrad(Si). After irradiation the threshold voltage of both the top Schottky gate and the back MOS gate shift to more negative values. The shift in threshold is attributed to radiation induced fixed oxide charge at the interface between the SOI channel and the buried oxide.Index Terms-MESFETs, silicon-on-insulator technology, X-ray effects.

Silicon-on-insulator MESFETs have been manufactured using a commercial SOI CMOS process and their electrical characteristics measured from room temperature up to 200° C. No modifications were made to the CMOS process flow. The prototype devices use a CoSi 2 gate material and the gate current follows the expected Shottky diode behavior. At room temperature a 0.6 µm gate length device has a threshold voltage of -0.8 V with an offstate drain current of approximately 5 nA. The device shows an attractive family of I-V curves up to 200° C. For higher temperatures the reverse diode current makes it hard to switch the device off. Numerical simulations of a similar device with a higher barrier height PtSi gate show reasonable behavior up to 300° C.