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金属与Ge材料接触时界面处存在着强烈的费米钉扎效应, 尤其与n型Ge形成的欧姆接触的比接触电阻率高, 是制约Si基Ge器件性能的关键因素之一. 本文对比了分别采用金属Al和Ni 与Si衬底上外延生长的p型Ge和n型Ge材料的接触特性. 发现在相同的较高掺杂条件下, NiGe与n型Ge可形成良好的欧姆接触, 其比接触电阻率 较 Al接触降低了一个数量级, 掺P浓度为21019 cm-3时达到1.4310-5 cm2. NiGe与p型Ge接触和Al接触的比接触电阻率相当, 掺B浓度为4.21018 cm-3时达到1.6810-5 cm2. NiGe与n型Ge接触和Al电极相比较, 在形成NiGe过程中, P杂质在界面处的偏析是其接触电阻率降低的主要原因. 采用NiGe作为Ge的接触电极在目前是合适的选择.Large contact resistance due to Fermi level pinning effect at the interface between metal and n-type Ge strongly restricts the performance of Ge device on Si substrate. In this paper, the contacts of metal Al and Ni with n-type Ge and p-type Ge epitaxial layers grown by UHV/CVD are comparatively studied. It is found that the contact of NiGe/n-Ge is better than that of Al/n-Ge at the same dopant concentration. When the concentration of P is 21019 cm-3, the ohmic contact of NiGe/n-Ge with c down to 1.4310-5 cm2 is demomstrated, which is about one order of magnitude lower than that of Al/n-Ge contact. The specific contact resistance of NiGe/p-Ge is 1.6810-5 cm2 when the B concentration is 4.21018 cm-3, corresponding to that of Al/p-Ge. Compared with Al/n-Ge contact, P segregation at the interface between NiGe and Ge, rather than lowering Schottky barrier height, is the main reseaon for achieving the low specific contact resistance. NiGe/Ge contact should be a good choice for contact electrode for Ge devices at present.
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Keywords:
- metal/Ge contact /
- NiGe /
- specific contact resistance
[1] Dimoulas A, Tsipas P, Sotiropoulos A, Evangelou E K 2006 Appl. Phys. Lett. 89 252110
[2] Camacho-Aguilera R E, Cai Y, Bessette J T, Kimerling L C, Michel J 2012 Opt. Mater. Express 2 1462
[3] Zhou Y, Ogawa M, Han X H, Wang K L 2008 Appl. Phys. Lett. 93 202105
[4] Kobayashi M, Kinoshita A, Saraswat K, Wong H S P, Nishi Y 2009 J. Appl. Phys. 105 023702
[5] Nishimura T, Kita K, Toriumi A 2008 Appl. Phys. Express 1 051406
[6] Jason Lin J Y, Roy A M, Nainani A, Sun Y, Saraswat K C 2011 Appl. Phys. Lett. 98 092113
[7] Martens K, Rooyackers R, Firrincieli A, Vincent B, Loo R, De Jaeger 2011 Appl. Phys. Lett. 98 013504
[8] Iyota M, Yamamoto K, Wang D, Yang H G, Nakashima H 2011 Appl. Phys. Lett. 98 192108
[9] Wu Z, Huang W, Li C, Lai H K, Chen S Y 2012 IEEE Trans. Electron. Dev. 59 1328
[10] Roy A M, Jason Lin J Y, Saraswat K C 2010 IEEE Electron Dev. Lett. 31 10
[11] Gallacher K, Velha P, Paul D, MacLaren I, Myronov M, Leadley D R 2012 Appl. Phys. Lett. 100 022113
[12] Li H J, Shi Y 2008 Semicond. Technol. 33 155 (in Chinese) [李鸿渐, 石瑛 2008 半导体技术 33 155]
[13] Cowley A, Sze S 1965 J. Appl. Phys. 36 3212
[14] Dimoulas A, Tsipas P, Sotiropoulos A, Evangelou E 2006 Appl. Phys. Lett. 89 252110
[15] Zang H, Lee S, Loh W, Wang J, Chua K, Yu M, Cho B, Lo G, Kwong D L 2008 IEEE Electron Dev. Lett. 29 161
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[1] Dimoulas A, Tsipas P, Sotiropoulos A, Evangelou E K 2006 Appl. Phys. Lett. 89 252110
[2] Camacho-Aguilera R E, Cai Y, Bessette J T, Kimerling L C, Michel J 2012 Opt. Mater. Express 2 1462
[3] Zhou Y, Ogawa M, Han X H, Wang K L 2008 Appl. Phys. Lett. 93 202105
[4] Kobayashi M, Kinoshita A, Saraswat K, Wong H S P, Nishi Y 2009 J. Appl. Phys. 105 023702
[5] Nishimura T, Kita K, Toriumi A 2008 Appl. Phys. Express 1 051406
[6] Jason Lin J Y, Roy A M, Nainani A, Sun Y, Saraswat K C 2011 Appl. Phys. Lett. 98 092113
[7] Martens K, Rooyackers R, Firrincieli A, Vincent B, Loo R, De Jaeger 2011 Appl. Phys. Lett. 98 013504
[8] Iyota M, Yamamoto K, Wang D, Yang H G, Nakashima H 2011 Appl. Phys. Lett. 98 192108
[9] Wu Z, Huang W, Li C, Lai H K, Chen S Y 2012 IEEE Trans. Electron. Dev. 59 1328
[10] Roy A M, Jason Lin J Y, Saraswat K C 2010 IEEE Electron Dev. Lett. 31 10
[11] Gallacher K, Velha P, Paul D, MacLaren I, Myronov M, Leadley D R 2012 Appl. Phys. Lett. 100 022113
[12] Li H J, Shi Y 2008 Semicond. Technol. 33 155 (in Chinese) [李鸿渐, 石瑛 2008 半导体技术 33 155]
[13] Cowley A, Sze S 1965 J. Appl. Phys. 36 3212
[14] Dimoulas A, Tsipas P, Sotiropoulos A, Evangelou E 2006 Appl. Phys. Lett. 89 252110
[15] Zang H, Lee S, Loh W, Wang J, Chua K, Yu M, Cho B, Lo G, Kwong D L 2008 IEEE Electron Dev. Lett. 29 161
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