We examine the microstructure of short-period (14–31 Å) composition modulations in epitaxial ZnSel-xTex (email@example.com) films grown by molecular-beam epitaxy (MBE) on vicinal (001) GaAs. Transmission electron microscope (TEM) images of cross-sections reveal highly-periodic contrast along the growth direction throughout the full thicknesses of the films (over 2 μm) that corresponds to a nearly sinusoidal variation between Se- and Te-rich compositions. Growth of ZnSe1-xTe x at 285°C on substrates tilted 4° toward [1111 maximizes the strength and regularity of the modulation. Using dynamical electron-diffraction simulations, we estimate a modulation amplitude of firstname.lastname@example.org(7) in a sample showing strong modulation. We assume a small amplitude of strain modulation to fit the experimental data.