Extreme asymmetric X‐ray Bragg reflection of semiconductor heterostructures near the edge of total external reflection

Synchrotron radiation has been used to measure the rocking curves from a (GaIn)(AsP) single layer grown on an InP (100)‐oriented substrate. For angles of incidence Φ B = ( Θ B − ϕ ) ≤ 0.7° measured at the Bragg angle Θ B ( ϕ is the angle between the diffracting lattice plane and the surface), the rocking curve (RC) is very strongly influenced by total external reflection (TER). This causes a decrease in the full width at half‐maximum (FWHM) and an asymmetrical shape for the RC for small Φ B . Both of these effects are due to the Bragg‐angle shift from the actual incident angle Φ which is not considered in the conventional dynamical theory. In this paper the essential influence of TER on any thin‐layer rocking curve is investigated using a numerical solution of the extended dynamical theory. The pattern can be interpreted up to Φ B ≥ Θ C ( Θ C is the angle of TER) by semiempirical incorporation of the results of the extended theory with the coupling formalism of Barrels, Hornstra & Lobeek [ Acta Cryst. (1986). A 42 , 539–545].