Total Ionizing Dose Radiation Effects in the P-Type Polycrystalline Silicon Thin Film Transistors

The total ionizing dose radiation effects in the polycrystalline silicon thin film transistors are studied. Transfer characteristics, high-frequency capacitance-voltage curves and low-frequency noises (LFN) are measured before and after radiation. The experimental results show that threshold voltage and hole-field-effect mobility decrease, while sub-threshold swing and low-frequency noise increase with the increase of the total dose. The contributions of radiation induced interface states and oxide trapped charges to the shift of threshold voltage are also estimated. Furthermore, spatial distributions of oxide trapped charges before and after radiation are extracted based on the LFN measurements.

Total Ionizing Dose Radiation Effects of RF PDSOI LDMOS Transistors

The effects of total ionizing dose radiation on direct current （DC） and small-signal radio frequency （RF） performance of multi-finger RF partial deplete silicon-on-insulator lateral double diffused MOS （PDSOI LDMOS） transistors are investigated. The radiation response of the LDMOS transistors with different device structures is characterized for an equivalent gamma dose up to 1Mrad（Si） at room temperature. The front and back gate threshold voltages, off-state leak- age, transconductance, and output characteristics are measured before and after radiation, and the results show a significant degradation of DC performance. Moreover, high frequency measurements for the irradiated transistors indicate remarkable declines of S-parameters, cutoff frequency, and maximum oscillation frequency to 1Mrad（Si） exposure levels. Compared to the transistors with the BTS contact structure,the transistors with the LBBC contact do not show its excellent DC radiation hardness when the transistors operate at alternating current （AC） mode.

Effect of total ionizing dose radiation on the 0.25 μm RF PDSOI nMOSFETs with thin gate oxide

Thin gate oxide radio frequency （RF） PDSOI nMOSFETs that are suitable for integration with 0.1μm SO1 CMOS technology are fabricated, and the total ionizing dose radiation responses of the nMOSFETs having four different device structures are characterized and compared for an equivalent gamma dose up to 1 Mrad （Si）, using the front and back gate threshold voltages, off-state leakage, transconductance and output characteristics to assess direct current （DC） performance. Moreover, the frequency response of these devices under total ionizing dose radiation is presented, such as small-signal current gain and maximum available/stable gain. The results indicate that all the RF PDSOI nMOSFETs show significant degradation in both DC and RF characteristics after radiation, in particular to the float body nMOS. By comparison with the gate backside body contact （GBBC） structure and the body tied to source （BTS） contact structure, the low barrier body contact （LBBC） structure is more effective and excellent in the hardness of total ionizing dose radiation although there are some sacrifices in drive current, switching speed and high frequency response.