To facilitate the production of HgCdTe IR detectors on Si substrates, epitaxial films of ZnTe and CdZnTe/ZnTe have been deposited by molecular-beam epitaxy (MBE) onto both Si(001) and Si(112) substrates. On Si(001) substrates misoriented from 0 to 8-degree toward [110], parallel epitaxy of ZnTe(001) and CdZnTe(001)/ZnTe(001) has bene observed. Using ZnTe initiation layers, high quality CdZnTe(001) films have been demonstrated with (004) reflection x-ray rocking curves as narrow as 158 arc-secs for Cd0.96Zn0.04Te and 78 arc-secs for CdTe. HgCdTe(001) films grown by liquid-phase epitaxy (LPE) on these MBE CdZnTe/ZnTe/Si(001) substrates have x-ray rocking curves as low as 55 arc-secs and average etch pit densities of 5 x 10(6) cm-2. IR detectors, fabricated from LPE-grown p-on-n heterojunctions on CdZnTe/Si, are comparable in performance to detectors on bulk CdZnTe substrates with R0A > 2 x 10(3) OMEGA-cm2 at 78 K for a 9.4 mum cutoff wavelength. On vicinal Si(112) substrates, ZnTe nucleates in either the (112) or twin (552) orientation, depending on the Si misorientation. CdTe deposited on ZnTe/Si(112) nucleates in the same orientation as the ZnTe. X-ray rocking curves as narrow as 110 arc-secs have been obtained for CdTe(552) epitaxy.