Random and channeling stopping powers of He and Li ions in Si

Abstract

In this work we have measured the electronic stopping powers of 4 He and 7 Li ions for channeling and random directions in Si as a function of the incident ion energy. The channeling (͗100͘ for Li, ͗110͘ and ͗111͘for Li and He͒ and the random ͑Li only͒ measurements cover a wide energy range between 200 keV and 9 MeV. The Rutherford backscattering technique together with different multilayer targets has been employed in the present experiments. The results are compared to calculations carried out in the framework of the unitary convolution approximation, which takes into account the impact-parameter-dependent energy loss for each projectile charge state, with further refinements including screening effects in close collisions between the electrons of the target and the screened projectile.

Stopping power measurements with the Time-of-Flight (ToF) technique

“…There are two main classes of methods for measuring stopping powers. The first class relies on back-scattering ions from materials [7,[17][18][19][20]; while in the second case, ions are transmitted through a thin foil [21][22][23][24]. Backscattering methods are ideally suited to measure the stopping powers of light ions in heavy materials (materials with high-Z elements).…”

“…Backscattering methods are ideally suited to measure the stopping powers of light ions in heavy materials (materials with high-Z elements). In addition of being able to measure stopping powers in random incident ion directions, this technique has also been adapted to measurements along ion channeling directions [18,20]. On the other hand, the transmission method is the more versatile of the two because it can be used both for light and heavy ions in Email address: fontana@pd.infn.it (Cristiano L. Fontana) light or heavy matrices.…”

Further improved technique for channeled stopping power measurements

“…Precise measurements [1][2][3] of absolute stopping powers in a thin film require comparison of the energy loss experienced by transmitted energetic ions with the areal density as determined by some other method (weighing or quartz crystal monitor). For practical applications, often the target being analyzed is a single crystal, and ions may be channeled which is known to reduce the stopping power [4][5][6]. For channeled stopping powers, it is not necessary to measure the stopping power absolutely; instead it suffices to compare the stopping power for channeled and ''random'' ions in the same film.…”

Validity of Bragg’s rule for heavy-ion stopping in silicon carbide

“…From an experimental aspect, most of the stopping studies deal with idealized situations: elemental targets. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Due to experimental difficulties in preparing and handling compound targets for energy-loss measurements, heavy-ion stopping data in compounds are very limited. 16 -20 Most studies have concentrated on the analysis of light ion stopping ͑H, He, and Li͒ in compounds composed of light elements.…”