Potential and stopping-power information from planar-channeling oscillations

Theoretical description of planar channeling process at small depths

“…I n consequence, one cannot perform averaging of the Fokker-Planck equation over the oscillation period of the ion motion a t small depths. Therefore, the solution of (1) by using the theory of anharmonic oscillations The spatial and angular distributions y1 and y2 can be calculated according to [13] in the following may : I n agreement with other authors [5,8,16] we assume that the quasichanneled ions are responsible for the structure of the backscattering spectra. These particles entering the crystal near the channel wall have a great close encounter probability.…”

“…If the energy loss can be neglected, the Fokker-Planck equation in the planar case is of the following form (see [ll]) : 8 , z, x,, 8,) is the particle distribution function, z the depth, x the distance from the channel centre, 8 the angle between the ion trajectory direction and the channel axis, 8, and x, are the initial conditions, w = W~( M /~E )~/~, where wo is the oscillation frequency in the harmonic field. q = 0.5(AO2/Az) describes the multiple scattering.…”

“…(8) Lindhard [20] also used an approximation to the Thomas-Fermi potential. Near the planes it is noticeably stronger than (7) and (8) was used. The parameters V , a n d a have been fitted both to (7) and (8).…”

Electron exchange influence on the energy loss of ions in SIMOX structure

“…The exchange cross-sections were determined from fitting of the solution of the propagation equations to the experimental date along the ETACHA procedure (Rozet et al, 1996). The nuclear encounter probability (NEP) (Barret, 1979) was calculated for each scattering event and stored as a function of the collision number and separately as a function of the energy loss. After scattering the straight line trajectory of ion from the point of scattering to the crystal surface (and to the detector) were assumed.…”

Planar channeling trajectories in diamond and silicon

“…4 to 7 ) . Our experimentally determined 212 values may now be compared to those calculated by Kiihrt and Wedell [12] and Rarrett [14]. Using the Fokker-Planck equation and the Molikre approximation to the Thomas-Fermi potential, Kiihrt and Wedell determined half wavelengths A12 which refer directly to our experiments.…”