Surface transient behavior of the ³⁰Si⁺ yield with angle of incidence and energy of an O⁺₂ primary beam

The width of the surface transient (w) from Si bombarded with oxygen ions has been investigated as a function of angle of beam incidence (0°≤θ≤75°) and as a function of primary energy (2–10 keV O⁺₂). The actual sputtered depth corresponding to this width has been determined using an internal depth marker. The width of this transient region is seen to increase with angle of incidence for 0°≤θ≤45°. For θ≥45°, w again decreases with increasing θ. The results are explained in terms of a model which calculates the sputtered depths taking into account SiO₂ formation (θ≤45°). For greater angles of incidence the sample retention model of the incident ions is seen to predict the angular dependence of the transition width. Computer simulations using Boltzmann transport equations are also performed which illustrate the validity of the above models and which closely agree with the experimental results.