Even though the strong Fermi-level pinning at the metal/germanium (Ge) interface can be alleviated by inserting a thin layer of tunneling oxide, the still sizeable Schottky barriers and the wide depletion regions of the Fe/oxide/ contacts make the junction resistances strongly dependent of temperature. The resistance-area (RA) products of these junctions are too high for spin injection and cannot be tuned by simply varying oxide thickness or using ferromagnetic metal (FM) with a lower work function. In this work, low energy ion implantation and rapid thermal annealing were utilized to degenerately dope the Ge surface layer to facilitate single-step tunneling transport. The RA products of the junctions with surface doping are significantly reduced and weakly dependent of temperature. This method gives a prospect for spin injection to Ge from FM.
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15 June 2009
Research Article|
June 18 2009
Engineering of tunnel junctions for prospective spin injection in germanium
Yi Zhou;
Yi Zhou
a)
1Department of Electrical Engineering, Device Research Laboratory,
University of California
, Los Angeles, California 90095, USA
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Masaaki Ogawa;
Masaaki Ogawa
1Department of Electrical Engineering, Device Research Laboratory,
University of California
, Los Angeles, California 90095, USA
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Mingqiang Bao;
Mingqiang Bao
1Department of Electrical Engineering, Device Research Laboratory,
University of California
, Los Angeles, California 90095, USA
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Wei Han;
Wei Han
2Department of Physics and Astronomy,
University of California
, Riverside, California 92521, USA
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Roland K. Kawakami;
Roland K. Kawakami
2Department of Physics and Astronomy,
University of California
, Riverside, California 92521, USA
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Kang L. Wang
Kang L. Wang
1Department of Electrical Engineering, Device Research Laboratory,
University of California
, Los Angeles, California 90095, USA
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a)
Electronic mail: yizhou@ee.ucla.edu.
Appl. Phys. Lett. 94, 242104 (2009)
Article history
Received:
February 03 2009
Accepted:
May 28 2009
Citation
Yi Zhou, Masaaki Ogawa, Mingqiang Bao, Wei Han, Roland K. Kawakami, Kang L. Wang; Engineering of tunnel junctions for prospective spin injection in germanium. Appl. Phys. Lett. 15 June 2009; 94 (24): 242104. https://doi.org/10.1063/1.3157128
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