Scott Messenger

Page 1. 2678 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 52, NO. 6, DECEMBER 2005 Displacement Damage Correlation of Proton and Silicon Ion Radiation in GaAs Jeffrey H. Warner, Scott R. Messenger, Robert J. Walters, and Geoffrey P. Summers ...

Abstract The use of nonionizing energy loss (NIEL) in predicting the effect of gamma, electron, and proton irradiations on Si, GaAs, and InP devices is discussed. The NIEL for electrons and protons has been calculated from the displacement threshold to 200 MeV. ...

An analysis of the effects of low energy proton irradiation on the electrical performance of triple junction (3J) InGaP2/GaAs/Ge solar cells is presented. The Monte Carlo ion transport code (SRIM) is used to simulate the damage profile induced in a 3J solar cell under the conditions of typical ground testing and that of the space environment. The results are used to present a quantitative analysis of the defect, and hence damage, distribution induced in the cell active region by the different radiation conditions. The modelling results show that, in the space environment, the solar cell will experience a uniform damage distribution through the active region of the cell. Through an application of the displacement damage dose analysis methodology, the implications of this result on mission performance predictions are investigated.

... This confusion stems from the fact that ground testing almost exclusively consists of unidirectional (typically normal-incidence), monoenergetic exposures while the space environment consists of an omni-directional, isotropic spectrum of particles. ...

Accurate prediction of solar cell performance in a space radiation environment is essential for selecting the appropriate cell technology for a given mission. A methodology for carrying out such assessments based on experimentally determined cell degradation as a function of electron and proton fluence has been applied successfully for many years. The necessary data to apply this methodology to novel cell types is usually not available, however, and it is imperative to be able to extract the maximum possible information from limited data. In this paper a new approach is outlined based on damage correlation using “displacement damage dose” which is derived from the product of the calculated nonionizing energy loss and the fluence. For electron damage it is found necessary in some cases to define a quantity “1 MeV electron equivalent dose” from which 1 MeV electron equivalent fluence can be calculated. With this new approach to damage correlation, it is possible to make accurate predictions of the expected degradation of solar cell performance in complex space radiation environments based on measurements made with only one proton energy and two electron energies, or with one proton and electron energy, and Co60 gammas. The power of the method is demonstrated using reported data for GaAs and Si cells

The effect of irradiating monolithic, two-terminal InP/Ga0.47 In0.53As tandem solar cells with 1 MeV electrons has been studied. These are the first solar cells of their kind to be produced. In addition, Ga0.47In0.53As single-junction cells with various base dopant levels grown to simulate the bottom cell of the tandem have been irradiated. The irradiation proceeded in incremental fluence steps from 6×1013 up to 1016 cm-2. The 1 sun, AMO I-V curve of each cell was measured after each fluence step. Before irradiation, efficiencies as high as 20% were measured on the tandem cells. The radiation resistance of the tandem cells is shown to be as high as that of an InP homojunction for fluences less than 3×1014 cm -2. For fluences greater than this, the bottom cell was seen to limit the cell current and thus degrade the tandem cell efficiency. It was found that the high base dopant level in the bottom cell served to increase the resistance of Voc but decrease the resistance of Isc. The data suggest that a base dopant level of around 2-5×1016 cm-3 in the bottom cell would significantly increase the resistance of Isc without seriously affecting Voc. In this way, a tandem cell can be designed which should remain current matched and produce efficiencies over 20% even after fluences well above 3×1014 cm-2

Page 1. IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 50, NO. 6, DECEMBER 2003 1919 NIEL for Heavy Ions: An Analytical Approach Scott R. Messenger, Edward A. Burke, Michael A. Xapsos, Geoffrey P. Summers, Robert J. Walters, Insoo Jun, and Thomas Jordan ...

Page 1. 2690 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 49, NO. 6, DECEMBER 2002 Application of Displacement Damage Dose Analysis to Low-Energy Protons on Silicon Devices Scott R. Messenger, Edward A. Burke, Geoffrey P. Summers, and Robert J. Walters ...

In this paper, the photovoltaic response of p+n and n+p GaAs solar cells is monitored as a function of proton fluence at different proton energies. The energy dependence of displacement damage coefficients (DCs) describing the photovoltaic degradation for these devices are compared with calculations of nonionizing energy loss (NIEL). The short circuit current DCs for both device types follows the same energy dependence. In contrast, the open circuit voltage DCs follows a different energy dependence at higher proton energies (E ≫ 10 MeV).

Page 1. 2276 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 52, NO. 6, DECEMBER 2005 Criteria for Identifying Radiation Resistant Semiconductor Materials Scott R. Messenger, Edward A. Burke, Geoffrey P. Summers, Robert J. Walters, and Jeffrey H. Warner ...