Effect of Trapped Charge Induced by Total Ionizing Dose Radiation on the Top-Gate Carbon Nanotube Field Effect Transistors

Abstract

The excellent performance and radiation-hardness potential of carbon nanotube (CNT) field effect transistors (CNTFETs) have attracted wide attention. However, top-gate structure CNTFETs, which are often used to make high-performance devices, have not been studied enough. In this paper, the total ionizing dose (TID) effect of the top-gate structure CNTFETs and the influence of the substrate on top-gate during irradiation are studied. The parameter degradation caused by the irradiation- and radiation-damage mechanisms of the top-gate P-type CNTFET were obtained by performing a Co-60 γ-ray irradiation test. The results indicate that the transfer curves of the top-gate P-type CNTFETs shift negatively, the threshold voltage and the transconductance decrease when TID increases, and the subthreshold swing decreases first and then increases with the increase in TID. The back-gate transistor is constructed by using the substrate as a back-gate, and the influence of back-gate bias on the characteristics of the top-gate transistor is tested. We also test the influence of TID irradiation on the characteristics of back-gate transistors, and reveal the effect of trapped charge introduced by radiation on the characteristics of top-gate transistors. In addition, the CNTFETs that we used have obvious hysteresis characteristics. After irradiation, the radiation-induced trapped charges generated in oxide and the OH groups generated by ionization of the CNT adsorbates aggravate the hysteresis characteristics of CNTFET, and the hysteresis window increases with the increase in TID.