Evaluation of Electrical Characteristics of MOSFET for Electron Beam Induced Effects

The space environment is hostile to most semiconductor electronic devices and components used for space applications and hence it is essential to assess the extent of radiation induced degradation in electrical characteristics of devices planned and used for space applications. Especially, the Van Allen Belts consist of high energy electrons which are in continuous motion. Satellites systems operating in Low Earth Orbits (LEO) are prone to get exposed to high energy electrons. This paper describes the effect of electron beam irradiation on MOSFETs planned for space applications. The devices selected for the study are 2N6768 n-channel MOSFETs (JANTXV) procured from ISAC, Bangalore. The decapped MOSFETS are exposed to a beam of electrons for various doses ranging from 50 Gy to 10 kGy in the electron energy range 7 - 10 MeV using the electron accelerator facility at RRCAT, Indore. Pre and post-irradiation measurements of the electrical characteristics are undertaken to investigate the electron induced device degradation and damage. The investigation reveals that there is a substantial increase in the leakage current and the transconductance also displays considerable reduction upon exposure to electron beam. These changes may be attributed to the trapped electron-holes pair in the gate oxide and Si/SiO2 interface. The increase in the leakage current can have significant effect on the device performance in a radiation environment.