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GaN films were grown on HVPE-AlN/SiC templates by metalorganic chemical vapor deposition (MOCVD) without annealing a reactor to eliminate memory effect. Step-terrace structure and smooth surface were obtained for GaN film with a thickness of ~200 nm. Subsequently, AlGaN/GaN heterostructures for the application of high electron mobility transistors (HEMTs) with thin GaN channel were fabricated with no C or Fe-doped GaN buffer layer. The interface quality at AlGaN/GaN heterostructure was good enough for two-dimensional electron gas (2DEG) to exhibit Shubnikov-de Haas oscillation in the magnetic field at 1.8 K. The GaN HEMTs with a thin channel on the AlN/SiC templates exhibited both pinch-off character and conventional properties. In view of both the shorter epitaxial-growth time and higher thermal conduction, HVPE-AlN/SiC templates are applicable to the fabrication of GaN HEMTs by MOCVD.