Effects of Hydrogen on the Radiation Response of Bipolar Transistors: Experiment and Modeling

Reactions of H₂ in lateral PNP BJTs are investigated through experiments and simulations. Pre-irradiation hydrogen exposure makes the devices more sensitive to ionizing radiation, which is explained through first-principles calculations and numerical simulations. Mechanisms for the cracking of hydrogen molecules and proton generation are proposed. We also suggest a mechanism of formation of border traps. When protons are trapped by oxygen vacancies right at or very near the interface, they form electrically active defects near the middle of the band gap. Activation energies of the reaction are used to construct rate equations. The rate equations are solved numerically to determine the spatial and temporal concentrations of hydrogen, holes, and protons. The calculated concentrations of interface and border traps agree well with the experimental results and help to explain the role of hydrogen in determining the total-dose response of BJTs.