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Gated Hybrid Hall Effect (HHE) devices on silicon Pratyush Das Kanungo, Alexandra Imre, Wu Bin, Alexei Orlov, Greg Snider, Wolfgang Porod Dept of Electrical Engineering, University of Notre Dame Nicholas.P.Carter Dept of Electrical and Computer Engineering, University of Illinois at Urbana Champaign Gated HHE Device – Structure and Physics Si MOSFET on Si Hall bar 25nm thick gate oxide,20micron gate length 20x12micron sized, 150nm thick ferromagnet on top of gate Hall effect on the 2DEG of inversion channel by the fringing field of ferromagnet Hall voltage read by passing current through the semiconductor Hall voltage/resistance changes with the direction of magnetization of the ferromagnet Binary magnetization states converted into bistable voltage Change of Hall voltage/resistance modulated by gate bias – effective way of controlling power dissipation Vg VH- e- e- I M VH+ Fringing field Ferromagnet Gate 2DEG Si Vg Change in magnetization direction (M) => Change in sign of Hall voltage (VH+ I to VH-) Change in gate voltage (Vg) => Change in magnitude of Hall voltage VH+ M e- e- VH- HHE device – magnetoelectronic system Information written as magnetization states by passing a write current through a current line HIGH, and LOW output Hall voltage according to direction of magntization. Good remanance in the ferromagnet may lead to hysteresis loop and hence memory Easily integrated with rest of the CMOS circuit Device structure HHE integrated with CMOS logic HHE device-interfacing MQCA MQCA Array Magnetic Quantum Cellular Automata (MQCA) cells can store information Different magnetic logics can be performed Can be fabricated on Si substrate at room temperature HHE device can interface MQCA with CMOS using the same principle of Hall effect Information can be stored, and processed magnetically, and will be read electrically Spin direction equivalent to logic “0” Spin direction equivalent to logic “1” Proposed device-MQCA interfaced with HHE devie Fabrication of HHE device-I Hall Bar defined in thick (240nm) field oxide by image reversal and mesa etch. Field oxide P type Si Metal (Ti/W) gate defined on top of Hall Bar, and n-wells formed through ion implantation Gate metal n well Gate oxide n well Fabrication of HHE device-II Gold bonding pads formed by image reversal and lift-off Metal bond pad n well n well Supermalloy deposited on top of the gate by e-beam lithography Supermalloy n well n well Fabricated HHE device, and MQCA at Notre Dame drain Magnetic dot Thirty three antiferromagnetically coupled magnetic dots – MQCA chain I gate drain source 4μ 12μ 10μ HHE device Magnet Magnetic domains in the ferromagnet Bistable Hall voltage and gate bias modulation Drop/increase of Hall voltage from HIGH to LOW modulated by gate bias More gate bias, less Hall voltage/voltage drop/increase, and vice versa HIGH B (external) B (external) VH VH+ VHI I Vg VH- LOW Magnet MagnetVH+ Vg B HIGH 1.21 0.750 HIGH 1.20 0.745 VH=48V VH(mV) VH(mV) 1.19 1.18 1.17 Field sweeping up Field sweeping down Vg=3V 1.16 -400 -200 VH=14V 0.735 Field sweeping up Field sweeping down Vg=4V 0.730 LOW 1.15 0.740 0 B(Gauss) 200 400 -400 LOW -200 0 B(Gauss) 200 400 Conclusion, and future direction of research Conclusion Switching of ferromagnets detected successfully – switching field 150 Gauss Gate bias modulation of Hall voltage demonstrated Future Research Shrinking the dimension of HHE device to submicron range Trying different magnetic material for broader hysteresis loop Amplifying the output hall voltage Integrating with MQCA, and fabricate a novel, cost effective, low power magnetoelectronic device on the same silicon substrate Building nonvolatile memory capable of instant ON operation