The authors compare the material properties of conventional- and interdiffused-grown layers of Hg_1-xCd_xTe/GaAs grown by metalorganic chemical vapour deposition (MOCVD). These results are also compared with those of state-of-the-art LPE HgCdTe/CdZnTe grown from Te-rich solutions. Data are presented on surface morphology, compositional uniformity, double-crystal X-ray diffraction, chemical defect etching, Hall effect, minority carrier lifetime and laser-beam-induced current (LBIC) characterisation on (111)B, (221) and (100) orientations. The compositional uniformity is 3.3% for 3 in diameter HgCdTe/GaAs. The interdiffused growth method results in better compositional uniformity than the conventional method, while the structural quality of layers grown by both techniques is similar. Etch pit densities of (1-2)*10⁶ cm^-2 are routinely obtained for (111)B and (221) orientations, while values as low as 5*10⁵ cm^-2 have been occasionally observed. Initial data are also presented for HgCdTe layers grown on (100)GaAs/Si substrates.