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Bipolar junction transistors (BJTs), as important electronic components in analog or mixed-signal integrated circuits (ICs) and BiCMOS (Bipolar Complementary Metal Oxide Semiconductor) circuits, are employed in the space environment. Therefore, the research on characteristics and mechanisms of ionization damage in the BJTs is very important. Lower energy electrons are used as irradiation source to study the ionization damage in NPN and PNP transistors. Various bias conditions are imposed on the emitter-base junction to reveal the different bias conditions that contribute to the radiation effect on NPN and PNP transistors during irradiation processing. The semiconductor parameter analyzer, Keithley 4200-SCS, is used to measure the change of electrical parameters of transistors with increasing electron irradiation fluence in situ. Based on the measurement results, we find the degradation of transistors is severe under reverse emitter-base bias, and is lowest under forward emitter-base bias, while it is medium under zero emitter-base bias at a given irradiation fluence.

In this paper,the degradation of irradiated GaAs/Ge single junction (SJ) solar cells is evaluated under the orbital environments using the displacement damage dose method. Firstly the electric-property changes of the SJ solar cells are experimentally obtained with the fluencies of electrons and protons of various energies under ground-based irradiation simulators. Based on the experimenal results and the calculated non-ionization energy losses (NIELs) of the electrons and protons in GaAs, the equivalent exponent n is obtained to be 1.7 for various electron energies,while the equivalent coefficient Rep for electron displacement damage converted into that of protons is 5.2. Furthermore, a degradation formula of the electrical property of the domestic SJ solar cell is established as a function of displacement damage dose during the particle irradiation. Using the displacement damage technique, the orbital evolution of the electric property degradation of the domestic SJ cell is predicted in this paper. In the meantime, the shielding effects of the cover glass with different thicknesses are also evaluated.

An investigation of ionization and displacement damage in silicon NPN bipolar junction transistors (BJTs) is presented. The transistors were irradiated separately with 90-keV electrons, 3-MeV protons and 40-MeV Br ions. Key parameters were measured in-situ and the change in current gain of the NPN BJTS was obtained at a fixed collector current (Ic = 1 mA). To characterise the radiation damage of NPN BJTs, the ionizing dose Di and displacement dose Dd as functions of chip depth in the NPN BJTs were calculated using the SRIM and Geant4 code for protons, electrons and Br ions, respectively. Based on the discussion of the radiation damage equation for current gain, it is clear that the current gain degradation of the NPN BJTs is sensitive to both ionization and displacement damage. The degradation mechanism of the current gain is related to the ratio of Dd/(Dd + Di) in the sensitive region given by charged particles. The irradiation particles leading to lower Dd/(Dd + Di) within the same chip depth at a given total dose would mainly produce ionization damage to the NPN BJTs. On the other hand, the charged particles causing larger Dd/(Dd + Di) at a given total dose would tend to generate displacement damage to the NPN BJTs. The Messenger–Spratt equation could be used to describe the experimental data for the latter case.