The structural, magnetic, and electrical properties of InMnAs thin films were investigated to elucidate their ferromagnetism for potential applications in InP-based spintronics and magneto-optical integrated circuits. The films were prepared on InP substrates by molecular beam epitaxy at growth temperatures of 220-280 degrees C without further annealing. Except for the 220 degrees C-grown sample, the films showed ferromagnetism at room temperature. We found that the room-temperature ferromagnetism was predominantly caused by the existence of hexagonal MnAs clusters embedded in a homogeneous InMnAs matrix (InMnAs:MnAs system). High-resolution transmission electron microscope images revealed that the MnAs nanoclusters formed either elongated or round structures in the InMnAs host matrix. The experimental results indicate that the mixed systems of hexagonal MnAs embedded in InMnAs may provide potential ferromagnetic building blocks for InP-based spintronics. (C) 2016 Elsevier B.V. All rights reserved.