Low-resistance ohmic contacts to p-ZnMgO grown by pulsed-laser deposition

Hyuck Soo Yang; Li, Y.; Norton, D. P.; Ip, K.; Pearton, S. J.; Soohwan Jang; Ren, F.
May 2005
Applied Physics Letters;5/9/2005, Vol. 86 Issue 19, p192103
Academic Journal
Electron-beam deposited Ni/Au is found to produce ohmic contacts to p-type ZnMgO (p∼1016 cm-3) after annealing in the range 300–450 °C. A minimum specific contact resistance of ∼10-2 Ω cm2 at room temperature and of 4×10-5 Ω cm2 at 473 K from circular transmission line measurements was obtained after annealing at 350 °C for 1 min in air. Higher anneal temperatures produced higher contact resistances and reaction of the contact metallurgy with diffusion of Ni to the surface of the Au layer where it became oxidized. The effective barrier height obtained from the measurement temperature dependence of the specific contact resistance, assuming thermionic emission, showed a value of 0.39±0.01 eV, much lower than the theoretical value of ∼2.4 eV. The difference in theoretical and experimental values is a clear indication of the strong role played by surface states, as reported earlier for Au Schottky contacts on ZnO.


Related Articles

  • Low-resistance and highly transparent Ni/indium-tin oxide ohmic contacts to phosphorous-doped p-type ZnO. Soon-Hyung Kang; Dae-Kue Hwang; Seong-Ju Park // Applied Physics Letters;5/23/2005, Vol. 86 Issue 21, p211902 

    The use of a Ni (50 Ã…)/indium tin oxide (ITO) (500 Ã…) bilayer scheme for low-resistance and transparent ohmic contacts to phosphorous doped p-type ZnO was investigated. Ni/indium tin oxide (ITO) (50/500 Ã…) layers were prepared by electron-beam evaporation. Although the as-deposited...

  • The mechanism of current flow in an alloyed In-GaN ohmic contact. Blank, T.; Gol'dberg, Yu.; Konstantinov, O.; Nikitin, V.; Posse, E. // Semiconductors;Oct2006, Vol. 40 Issue 10, p1173 

    The resistance of alloyed In-GaN ohmic contact is studied experimentally. In the temperature range 180–320 K, the resistance per unit area increases with temperature, which is typical of metallic conduction and disagrees with current flow mechanisms associated with thermionic,...

  • Highly low resistance and transparent Ni/ZnO ohmic contacts to p-type GaN. Song, June O; Kim, Kyoung-Kook; Park, Seong-Ju; Seong, Tae-Yeon // Applied Physics Letters;7/21/2003, Vol. 83 Issue 3, p479 

    We report on a promising Ni (5 nm)/Al-doped ZnO (AZO) (450 nm) metallization scheme for low resistance and transparent ohmic contacts to p-GaN (5 × 10[SUP17]cm[SUP-3]). It is shown that the as-deposited Ni/AZO contact shows a nonohmic characteristic due to the insulating nature of the...

  • Thermally driven defect formation and blocking layers at metal-ZnO interfaces. Mosbacker, H. L.; Zgrabik, C.; Hetzer, M. J.; Swain, A.; Look, D. C.; Cantwell, G.; Zhang, J.; Song, J. J.; Brillson, L. J. // Applied Physics Letters;8/13/2007, Vol. 91 Issue 7, p072102 

    The authors used depth-resolved cathodoluminescence spectroscopy and current-voltage measurements to probe the temperature-dependent formation of native point defects and reaction layers at metal-ZnO interfaces and their effect on transport properties. These results identify characteristic...

  • Comment on “Contact mechanisms and design principles for alloyed Ohmic contacts to n-GaN” [J. Appl. Phys. 95, 7940 (2004)]. Yow-Jon Lin // Journal of Applied Physics;10/1/2006, Vol. 100 Issue 7, p073707 

    The contact mechanism and design principles for alloyed Ohmic contacts to n-GaN were investigated in Mohammad’s paper [J. Appl. Phys. 95, 7940 (2004)]. Mohammad’s study demonstrated that both tunneling and thermionic emission were equally important for low resistivity at the...

  • Ohmic contacts to n+-GaN capped AlGaN/AlN/GaN high electron mobility transistors. Wang, Liang; Mohammed, Fitih M.; Ofuonye, Benedict; Adesida, Ilesanmi // Applied Physics Letters;7/2/2007, Vol. 91 Issue 1, p012113 

    Investigations of Ti/Al/Mo/Au Ohmic contact formation, premetallization plasma treatment effects, and interfacial reactions for n+-GaN capped AlGaN/AlN/GaN heterostructures are presented. Ti thickness played an important role in determining contact performance. Transmission electron microscopy...

  • V/Al/V/Ag Ohmic contacts to n-AlGaN/GaN heterostructures with a thin GaN cap. Miller, M. A.; Mohney, S. E. // Applied Physics Letters;7/2/2007, Vol. 91 Issue 1, p012103 

    Silver is studied as a replacement for Au in V- and Ti-based Ohmic contacts to GaN-capped n-Al0.27Ga0.73N/GaN heterostructures for high electron mobility transistors. An optimized V/Al/V/Ag contact provided a low contact resistance of 0.27 Ω mm and specific contact resistance of 1.7×10-6...

  • Structural and electrical characterization of AuPdAlTi ohmic contacts to AlGaN/GaN with varying Ti content. Fay, M.W.; Moldovan, G.; Weston, N.J.; Brown, P.D.; Harrison, I.; Hilton, K.P.; Masterton, A.; Wallis, D.; Balmer, R.S.; Uren, M.J.; Martin, T. // Journal of Applied Physics;11/15/2004, Vol. 96 Issue 10, p5588 

    AuPdAlTi/AlGaN/GaN ohmic contact structures with varying Ti:Al ratios have been investigated. The relationship between Ti:Al ratio, interfacial microstructure, and contact resistance is examined. Rapid thermal annealing temperatures of 850 °C or higher are required to produce an ohmic contact...

  • Formation mechanism of Ohmic contacts on AlGaN/GaN heterostructure: Electrical and microstructural characterizations. Wang, Liang; Mohammed, Fitih M.; Adesida, Ilesanmi // Journal of Applied Physics;May2008, Vol. 103 Issue 9, p093516 

    The electrical characteristics and interfacial reactions of Ti/Al/Mo/Au metallization on AlGaN/GaN heterostructures at various annealing temperatures ranging from 400 to 950 °C have been investigated in an effort to elucidate the Ohmic contact formation mechanism. A transition from Schottky...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics