SEMICONDUCTOR DEVICES

Self-aligned graphene field-effect transistors on SiC (0001) substrates with self-oxidized gate dielectric

Jia Li1, Cui Yu1, Li Wang2, Qingbin Liu1, Zezhao He1, Shujun Cai1 and Zhihong Feng1,

+ Author Affiliations

 Corresponding author: Feng Zhihong, Email:ga917vv@163.com

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Abstract: A scalable self-aligned approach is employed to fabricate monolayer graphene field-effect transistors on semi-insulated 4H-SiC (0001) substrates. The self-aligned process minimized access resistance and parasitic capacitance. Self-oxidized Al2O3, formed by deposition of 2 nm Al followed by exposure in air to be oxidized, is used as gate dielectric and shows excellent insulation. An intrinsic cutoff frequency of 34 GHz and maximum oscillation frequency of 36.4 GHz are realized for the monolayer graphene field-effect transistor with a gate length of 0.2 μm. These studies show a pathway to fabricate graphene transistors for future applications in ultra-high frequency circuits.

Key words: graphemeself-alignedtransistors



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[5]
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[8]
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[9]
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[10]
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[11]
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[12]
Wu Y Q, Lin Y M, Jenkins K A, et al. RF performance of short channel graphene field-effect transistor. IEDM, 2010: 9. 6. 1
[13]
Fiori G, Iannaccone G. Insights on radio frequency bilayer graphene FETs. IEDM, 2012: 17. 3. 1
[14]
Guo Z L, Dong R, Chakraborty P S, et al. Record maximum oscillation frequency in C-face epitaxial graphene transistors. Nano Lett, 2013, 13(3): 942 doi: 10.1021/nl303587r
[15]
Bai J W, Liao L, Zhou H L, et al. Top-gated chemical vapor deposition grown graphene transistors with current saturation. Nano Lett, 2011, 11(6): 2555 doi: 10.1021/nl201331x
[16]
Xu H L, Zhang Z Y, Xu H T, et al. Top-gated graphene field-effect transistors with high normalized transconductance and designable Dirac point voltage. ACS Nano, 2011, 5(6): 5031 doi: 10.1021/nn201115p
[17]
Badmaev A, Che Y, Li Z, et al. Self-aligned fabrication of graphene RF transistors with T-shaped gate. Acs Nano, 2012, 6: 3371 doi: 10.1021/nn300393c
[18]
Kim K, Choi J Y, Kim T, et al. A role for graphene in silicon-based semiconductor devices. Nature, 2011, 479: 338 doi: 10.1038/nature10680
Fig. 1.  (Color online) Schematic illustration of self-aligned graphene transistor process flow. (a) Monolayer graphene on Si-face 4H-SiC. (b) T-gates were patterned using e-beam lithography, with trilayer electron beam resist. (C) Two nm Al was deposited and exposed in air to form Al2O3 dielectric. (d) T-gate stack was deposited. (e) After lift-off, T-gate stands on graphene. (f) The self-aligned source and drain were created by depositing 20 nm Au metal.

Fig. 2.  (a) AFM image of epitaxial graphene grown on SiC, showing the terrace structure. (b) Representative Raman spectra of the epitaxial graphene. The Raman signal of epitaxial graphene was obtained by subtracting the signal of bare SiC. (c) Lorentzian fits of 2D peak.

Fig. 3.  (a) AFM image of the self-oxidized Al2O3 dielectric. (b) Gate leakage current of the graphene transistor.

Fig. 4.  DC characteristics of the self-aligned graphene transistor with 200 nm gate length. (a) Ids-Vds output characteristics of the device at various gate voltages. (b) The transfer characteristic of the device at different drain voltages. (c) The extracted transconductance, Gm = dIds/dVgs, for the device with different Vds.

Fig. 5.  (Color online) Current and power gains versus frequency for an Lch = 200 nm device. (a) Current gain $\vert H_{21}\vert $ before (fT = 15.9 GHz) and after de-embedding (fT = 34 GHz). (b) Maximum available gain (MAG) before (fmax = 20 GHz) and after de-embedding (fmax = 36.4 GHz).

[1]
Geim A K, Novoselov K S. The rise of graphene. Nature Mater, 2007, 6: 183 doi: 10.1038/nmat1849
[2]
Booth T J, Blake P, Nair R R, et al. Macroscopic graphene membranes and their extraordinary stiffness. Nano Lett, 2008, 8(8): 2442 doi: 10.1021/nl801412y
[3]
Cheng R, Bai J W, Liao L, et al. High-frequency self-aligned graphene transistors with transferred gate stacks. PNAS, 2012, 109(29): 11588 doi: 10.1073/pnas.1205696109
[4]
Liao L, Lin Y C, Bao M Q, et al. High-speed graphene transistors with a self-aligned nanowire gate. Nature, 2010, 467: 305 doi: 10.1038/nature09405
[5]
Badmaev A, Che Y C, Li Z, et al. Self-aligned fabrication of graphene RF transistors with T-shaped gate. ACS Nano, 2012, 4: 3371 https://scholars.opb.msu.edu/en/publications/self-aligned-fabrication-of-graphene-rf-transistors-with-t-shaped-2
[6]
First P N, de Heer W A, Seyller T, et al. Epitaxial graphenes on silicon carbide. MRS Bull, 2010, 35: 296 doi: 10.1557/mrs2010.552
[7]
Ray N, Shallcross S, Hensel S, et al. Buffer layer limited conductivity in epitaxial graphene on the Si face of SiC. Phys Rev B, 2012, 86: 125426 doi: 10.1103/PhysRevB.86.125426
[8]
Lin Y M, Farmer D B, Jenkins K A, et al. Enhanced performance in epitaxial graphene FETs with optimized channel morphology. IEEE, 2011, 32(10): 1343 http://ieeexplore.ieee.org/iel5/55/6028517/06012508.pdf
[9]
Ni Z, Wang Y, Yu T, et al. Raman spectroscopy and imaging of graphene. Nano Res, 2008, 1(4): 273 doi: 10.1007/s12274-008-8036-1
[10]
Lee D S, Riedl C, Krauss B, et al. Raman spectra of epitaxial graphene on SiC and of epitaxial graphene transferred to SiO2. Nano Lett, 2008, 8(12): 4320 doi: 10.1021/nl802156w
[11]
Lin Y M, Dimitrakopoulos C, Jenkins K A, et al. 100-GHz Transistors from wafer-scale epitaxial graphene. Science, 2010, 327: 662 doi: 10.1126/science.1184289
[12]
Wu Y Q, Lin Y M, Jenkins K A, et al. RF performance of short channel graphene field-effect transistor. IEDM, 2010: 9. 6. 1
[13]
Fiori G, Iannaccone G. Insights on radio frequency bilayer graphene FETs. IEDM, 2012: 17. 3. 1
[14]
Guo Z L, Dong R, Chakraborty P S, et al. Record maximum oscillation frequency in C-face epitaxial graphene transistors. Nano Lett, 2013, 13(3): 942 doi: 10.1021/nl303587r
[15]
Bai J W, Liao L, Zhou H L, et al. Top-gated chemical vapor deposition grown graphene transistors with current saturation. Nano Lett, 2011, 11(6): 2555 doi: 10.1021/nl201331x
[16]
Xu H L, Zhang Z Y, Xu H T, et al. Top-gated graphene field-effect transistors with high normalized transconductance and designable Dirac point voltage. ACS Nano, 2011, 5(6): 5031 doi: 10.1021/nn201115p
[17]
Badmaev A, Che Y, Li Z, et al. Self-aligned fabrication of graphene RF transistors with T-shaped gate. Acs Nano, 2012, 6: 3371 doi: 10.1021/nn300393c
[18]
Kim K, Choi J Y, Kim T, et al. A role for graphene in silicon-based semiconductor devices. Nature, 2011, 479: 338 doi: 10.1038/nature10680
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    Received: 05 November 2013 Revised: 19 December 2013 Online: Published: 01 July 2014

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      Jia Li, Cui Yu, Li Wang, Qingbin Liu, Zezhao He, Shujun Cai, Zhihong Feng. Self-aligned graphene field-effect transistors on SiC (0001) substrates with self-oxidized gate dielectric[J]. Journal of Semiconductors, 2014, 35(7): 074006. doi: 10.1088/1674-4926/35/7/074006 J Li, C Yu, L Wang, Q B Liu, Z Z He, S J Cai, Z H Feng. Self-aligned graphene field-effect transistors on SiC (0001) substrates with self-oxidized gate dielectric[J]. J. Semicond., 2014, 35(7): 074006. doi: 10.1088/1674-4926/35/7/074006.Export: BibTex EndNote
      Citation:
      Jia Li, Cui Yu, Li Wang, Qingbin Liu, Zezhao He, Shujun Cai, Zhihong Feng. Self-aligned graphene field-effect transistors on SiC (0001) substrates with self-oxidized gate dielectric[J]. Journal of Semiconductors, 2014, 35(7): 074006. doi: 10.1088/1674-4926/35/7/074006

      J Li, C Yu, L Wang, Q B Liu, Z Z He, S J Cai, Z H Feng. Self-aligned graphene field-effect transistors on SiC (0001) substrates with self-oxidized gate dielectric[J]. J. Semicond., 2014, 35(7): 074006. doi: 10.1088/1674-4926/35/7/074006.
      Export: BibTex EndNote

      Self-aligned graphene field-effect transistors on SiC (0001) substrates with self-oxidized gate dielectric

      doi: 10.1088/1674-4926/35/7/074006
      Funds:

      the National Natural Science Foundation of China 61306006

      Project supported by the National Natural Science Foundation of China (No. 61306006)

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      • Corresponding author: Feng Zhihong, Email:ga917vv@163.com
      • Received Date: 2013-11-05
      • Revised Date: 2013-12-19
      • Published Date: 2014-07-01

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