AVS 46th International Symposium
    Magnetic Interfaces and Nanostructures Technical Group Wednesday Sessions
       Session MI+EM-WeM

Paper MI+EM-WeM6
Novel Hybrid Magnetoelectronic Device for Magnetic Field Sensing

Wednesday, October 27, 1999, 10:00 am, Room 618/619

Session: Spin-Dependent Tunneling and Transport
Presenter: D.M. Schaadt, University of California, San Diego
Authors: D.M. Schaadt, University of California, San Diego
E.T. Yu, University of California, San Diego
S. Sankar, University of California, San Diego
A.E. Berkowitz, University of California, San Diego
Correspondent: Click to Email
Structures in which magnetic and electronic materials are combined offer a variety of possibilities for realization of devices with dramatically improved functionality or performance as compared to conventional devices. We have designed, characterized, and analyzed a novel hybrid magnetoelectronic device: a monolithic field-effect-transistor-amplified magnetic field sensor in which a granular Co-SiO@sub2@ tunnel magnetoresistive (TMR) thin film is incorporated into the gate of a p-channel Si metal-oxide-semiconductor field-effect transistor (MOSFET). In this structure, current flow through the TMR film leads to a buildup of electronic charge within the gate, and consequently to a transistor threshold voltage shift. For a fixed voltage applied across the TMR layer, an external magnetic field changes the TMR film resistance, and consequently the current and charge within the gate. The resulting threshold voltage shift leads to a pronounced response to the external magnetic field in the transistor current-voltage characteristics. The relative current change induced by application of a 6 kOe external magnetic field at room temperature was amplified from 5% for the current through the TMR film to 21% for the transistor subthreshold current. The absolute current response in the saturation regime increased by a factor of about 500 compared to that of the TMR film alone. These results were achieved in a non-optimized device structure; substantially better performance should be achievable with relatively straightforward improvements in device design and processing. A detailed analysis of the operation of this device and of methods for optimization of performance will be presented.