Methods of forming structures that include InP-based materials, such as a transistor operating as an inversion-type, enhancement-mode device are disclosed. A dielectric layer may be deposited by ALD over a semiconductor layer including In and P. A channel layer may be formed above a buffer layer having a lattice constant similar to a lattice constant of InP, the buffer layer being formed over a substrate having a lattice constant different from a lattice constant of InP.