Linear Energy Transfer of Heavy Ions in Silicon

Researchers performing radiation testing on electronic components often rely on semi-empirical prediction codes for determining the linear energy transfer (LET) (or electronic stopping force) of ions, without paying much attention to their reliability. However, it is seen that estimations calculated with different codes can have over 10% discrepancies, especially in the case of heavy ions with higher LET (e.g., xenon). As a consequence of the modern component fabrication techniques this has become an important issue when studying the radiation durability of electronics. In order to clarify this inconsistency, LET measurements for $^{131}$Xe and $^{82}$Kr in silicon have been undertaken and obtained results are presented, discussed and compared with earlier predicted data.

I. Introduction

The Radiation Effects Facility (RADEF) [1], [2] at JYFL Accelerator Laboratory, Jyväskylä, Finland, is one of the European Space Agency's European Component Irradiation Facilities (ECIF). This facility has developed and regularly utilizes a heavy ion cocktail with an energy of 9.3 A MeV [3], [4]. This selection of ions includes seven different ion species from N to Xe. These can be used to cover linear energy transfer (LET) values in silicon from about 2 to 60 MeV/mg/cm² for the use of single event effect (SEE) studies in semiconductor components. TableI summarizes the characteristics of the various ions included in this cocktail. The LET and range information for ions in silicon is given as calculated with the SRIM [5], [6] and LET Calculator [7] codes.