| Spin based electronics, commonly referred to as "spintronics", seeks to expand the functionalities of microelectronic devices by introducing the ability to manipulate the carrier's spin, in addition to or instead of its charge. Key steps in spintronic devices include the injection, manipulation and detection of the carrier's spin. Metal-based spintronic devices such as spin valves have already found applications in high capacity hard disk drive read heads and have potential in non-volatile solid state memories. However, in order to realize the full potential of spintronics, spin manipulation must be introduced into semiconductor devices. This in turn, requires the development of magnetic semiconductors.;Dilute magnetic semiconductors (DMS) are a class of magnetic semiconductors in which a fraction of the cations are substitutionally replaced by magnetic ions. The exchange interaction between the spin of the dopant atoms and the carriers in the semiconductor host is expected to bring about global ferromagnetic order in the entire lattice in these materials. The search for novel DMS candidates has been driven by two cardinal requirements - a material system with well-developed growth technology, and a high Curie temperature.;In this work, we have investigated the growth and characteristics of one such promising candidate, transition-metal doped InN. InN films were deposited on c-sapphire substrates by molecular beam epitaxy, employing GaN underlayers to reduce the lattice mismatch between the film and substrate. The films were doped from 0.1-6% Cr with no noticeable trace of crystalline secondary phases detected by X-ray diffraction. However, Mn-doping led to segregation of manganese nitride. Hall effect measurements revealed n-type behavior in both undoped as well as Cr-doped films. A magnetic hysteresis, with a small remanence and coercivity was observed in Cr:InN up to room temperature, confirming long-range magnetic order in this material. X-ray magnetic circular dichroism experiments revealed dichroism at the Cr L-edge, indicating that the Cr in the matrix was magnetically active. However, deeper probing of the magnetic behavior revealed some metastable characteristics. Thus, the structure as well as magnetic and electrical properties of this novel DMS candidate was studied in this work. |
