The Hg1−xCdxTe films with a small concentration of Cd and a narrow band gap have been prepared on GaAs(100) substrates by using the ionized cluster beam (ICB) technique. For the case of ionizing clusters of either CdTe or HgTe as source materials, the band gap can be controlled between 0.2 and 0.3 eV by adjusting the acceleration voltage for cluster ions. The kinetic energy and the ionic charge of the cluster ions are found to have much influence on the composition and the optical properties of the films.