Carrier-induced ferromagnetism in (Ga,Fe)N

Semiconductor spin transfer electronics (spintronics) represents a key research area with the aim of employing rather the spins of single electrons, than their charge for storing, transmitting and processing quantum information. The expected advantages of spin devices include non-volatility of stored information, higher integration density, lower power operation and higher switching speed. It is expected that new functionalities for electronics and photonics can be achieved if the injection, transfer and detection of carrier spin can be controlled above room temperature. A promising family of materials systems for spintronics is represented by diluted magnetic semiconductors (DMS). A recent theoretical work was the breakthrough that focused attention on nitride-based DMS as being most promising for achieving practical ordering temperatures. According to the mentioned theoretical model, itinerant holes are essential for the mediation of the long-range ferromagnetic interactions. While most of the theoretical and experimental work for DMS materials has focused, to date, on the use of Mn as the magnetic dopant, room temperature carrier-mediate ferromagnetism has not yet been achieved and there start to be some progress in identifying other transition metal atoms that may be employed to trigger the mechanism at practical temperatures. Iron, for example. The value of exchange energy, crucial for the onset of carrier-induced mechanism, has been estimated for (Ga,Fe)N to be such that ferromagnetism at room temperature can be expected, provided that free holes can be introduced. In the frame of the proposed project, for the first time both hexagonal and cubic p-type GaN doped with Fe and grown by means of metal-organic chemical vapour deposition will be thoroughly studied in the perspective of achieving (or ruling out) room-temperature carrier-mediated ferromagnetism.