Gamma and Electron NIEL Dependence of Irradiated GaAs

Abstract

In GaAs material, the radiation-induced degradations are demonstrated to vary according to the Non Ionizing Energy Loss (NIEL). But some discrepancies are still observed between experimental degradation measurements and predicted NIELs. The used displacement threshold energy (T d ) varies, from one author to another, from 10 eV up to 25 eV. A measurement made with 60 Co gamma rays is used to investigate the relevance of the NIEL scaling law for both electrons and gamma rays. A T d value of 21 eV is found to be the most appropriate value, to properly scale the present experimental degradation measurements.

Gamma non-ionizing energy loss: Comparison with the damage factor in silicon devices

“…These secondary electrons are slowed down by shielding before they leave to produce displacement damage in the active region of the device. In order to calculate the NIEL of 60 Co gamma rays ( 60 Co NIELγ) we have to integrate the slowed down spectrum of secondary electrons with the amount of atomic displacements produced by these secondary electrons (i.e., the electrons NIEL), the gamma NIEL is expressed as [18].…”

“…This slowed down spectrum can vary, if a device or tested material is surrounded by heavy materials, and also depends on the thickness of such materials. It has been reported that the difference in equilibrium spectra between lighter materials and heavy materials could be up to 40% [18]. [11].…”

“…But, in the case of electrons and gamma rays, a significant deviation from linearity of K d with the NIEL calculations is observed [1,[6][7][8][9]. Because of the greater availability of electron accelerators and gamma sources for laboratory testing and simulation of radiation environments and effects, some efforts focused on developing the NIEL prediction for both electrons and gamma rays [13][14][15][16][17][18] have been performed. Inguimbert et al [13] proposed a new approach that includes molecular dynamic results, which could explain the quadratic dependence of the damage factor found in silicon following electron irradiation [9].…”

Degradation fitting of irradiated solar cells using variable threshold energy for atomic displacement

“…There are various T d values reported in the literature according to varying defect levels introduced in the semiconductor band gap [17][18][19]. In the recent work of El Allam et al [20], discrepancies throughout literature are summarized concerning the scaling of experimental GaAs data with NIEL. Their work highlights that a value of threshold energy for atomic displacement in the range of 15-21 eV is best suited to fit experimental degradation measurements for many GaAs data.…”

Damage Factor for Radiation-Induced Dark Current in InGaAs Photodiodes

“…The Compton electrons scattered during the interaction of γrays with matter can also induce displacement damage. The displacement damage dose generated by these Compton electrons was calculated using a NIEL value provided in [21]. In this reference the NIEL of 60 Co γ-rays have been calculated for GaAs.…”