The electrical and photo-electronic properties of graphene-based field effect transistors (GFETs) were studied when the single layer graphene served as the transistor channel, while interfaced with well organized, isolated semiconductor quantum dots (QD) array. The photoluminescence (PL) of the QDs as a function of the drain-source (Vds) and the gate-source (Vgs) bias was studied.

Graphene, a two-dimensional, single layer thick crystalline form of carbon atoms, has outstanding physical properties, such as high conductivity, chemical inertness, mechanical robustness and unusual dispersion relations [1]. In the past, we studied graphene layer(s) when suspended over nano-pore structures [2-6]. Here we used anodized aluminum oxide (AAO) as the perforated substrate, and core/shell CdSe/ZnS semiconductor quantum dots (QD) as the photo-sensitive material. The QD were imbedded in the AAO pores.

The GFETs were fabricated by transferring a single layer of graphene on top of the QD imbedded AAO. The array of holes on the AAO substrate were 25-30 nm in diameter and with a pitch of 100 nm. For the photoluminescence (PL) measurements, a 10 mW Ar ion laser at 488 nm was used in confocal arrangement. Coupling of the incident and/or emitted light with the surface Plasmon/Polariton (SPP) mode was observed as a peak in PL curve as a function of the sample's tilt angle with respect to the incident optical beam. The fluorescence peak of the QDs decreased monotonously as a function of Vgs and Vds alluding to the control of PL by the biasing potentials. The effect of white-light intensity on the sample conductivity was studied, as well: the difference in Ids between illuminated and non-illuminated cases was substantially affected by the biasing potentials.

[1]           K.S. Novoselov, A.K. Geim, S.V. Morozov, D. Jiang, Y. Zhang, S.V. Dubonos, I.V. Grigorieva and A.A. Firsov, “ Electric Field Effect in Atomically Thin Carbon Films”,  Science, 306, 666 (2004).

[2]           A. Banerjee, R. Li and H. Grebel, “Surface Enhanced Raman with Graphenated Anodized Aluminum Oxide Substrates: the Effect of Sub-Wavelength Patterns”, Nanotechnology, 20 (29), art. no. 295502 (2009).

[3]           A. Banerjee and H. Grebel, “Depositing Graphene Films on Solid and Perforated Substrates”, Nanotechnology, 19 1-5 art. no. 365303 (2008).

[4]           Ruiqiong Li, and Grebel Haim, “Surface Enhanced Fluorescence”, IEEE Sensors, 10(3), 465-468 (2010) doi: 10.1109/JSEN.2009.2038513.

[5]           R. Li, A. Banerjee and H. Grebel, “The possibility for surface plasmon lasers”, Optics Express, 17, 1622-1627 (2009).

[6]           A. Banerjee, R. Li and H. Grebel, "Surface plasmon lasers with quantum dots as gain media", Appl. Phys. Letts., 95, 251106 (2009); doi:10.1063/1.3276273.