PLANAR CHANNELING IN SUPERLATTICES .3. POTENTIAL AND PARAMETER DEPENDENCE OF CATASTROPHIC DECHANNELING

Catastrophic planar dechanneling in strained-layer superlattices provides for a critical evaluation of fundamental-particle channeling phenomena, as well as a method of strain assessment. Using continuum-model theory, the equation of projectile motion is solved numerically. The depth and angular dependences of catastrophic dechanneling are examined as a function of the parameters: incident energy and angle, superlattice strain, crystal potential, and the minimum impact parameter for channeling. The catastrophic dechanneling increases with the strain-induced tilt angle and contains well-defined structures in the angular and depth dependences. These features are particularly sensitive to strain for the region 0.1 to 1.0 times the critical angle for channeling. Also, there is a range of energies (10%) about the resonant value for which good catastrophic dechanneling behavior is retained. Using the thermally averaged Doyle-Turner potential and data from a GaAsxP1-x/GaP superlattice, we obtain a minimum impact parameter for planar channeling of 1.3 times the Thomas-Fermi screening length. When scaled by thermal vibrational amplitude, this value (2.3u1, where u1 is the one-dimensional amplitude) is consistent with recent computer-simulation results for the steering of particles by single-crystal planes. © 1990 The American Physical Society.