Dilute Magnetic Semiconductors
Our group has been examining ultrathin magnetic films of conductive metals, insulating oxides and dilute magnetic semiconductors for application in electronic communication, and broad-band sensor technologies.
The field of spin transport electronics is rapidly evolving since potential devices will have charge and spin degrees of freedom in a single material. Of particular importance in realizing these devices is that the host material be ferromagnetic above room temperature. Also, it is necessary to have both efficient spin polarized carrier injection and transport. The spin injection efficiency is usually low for ferromagnetic metals. Therefore, the research field of Dilute Magnetic Semiconductors (DMS) has attracted much attention because DMS can be used to efficiently inject spin polarized carriers. DMS refers to semiconductor alloys, in which a fraction of the host atoms are replaced by transition metal atoms, thus inserting a local magnetic moment into the matrix, and with proper doping levels a high moment/dopant can be achieved. Typical semiconducting lattices include ZnO, TiO2, and SnO2, while popular dopants include Mn, Ni, Fe, Cr, and Co.
Our current work is focused on Co:TiO2. TiO2 is a wide bandgap semiconductor with high transmission in the visible and far infrared regions, a high refractive index, a high dielectric constant, and a high mobility of n-type charge carriers.