Since the discovery of graphene in 2004 by Novoselov and Geim, a lot of research emphasis has been directed towards
its characterization. Most of the important scientific breakthroughs have been obtained on exfoliated graphene (produced via the well known ‘scotch tape’ method), nowadays, different synthetic routes have been developed to obtain largescale graphene. Among several optical techniques, Raman spectroscopy is the one most often employed to characterize the defects, number of graphene layers and other properties of the graphitic films regardless of their fabrication method. In this work, we will report on the microscopic imaging of the two-photon fluorescence (2PF) properties and the second harmonic generation (SHG) in both single layer and few layer graphene.
Graphene possesses unique physical properties, due to its specific energy bands configuration, substantially
different from that of materials traditionally employed in solid-state optoelectronics. Among the variety of remarkable
properties, strong field effect, high transparency in the visible-light range and low resistivity of graphene sheets are the
most attractive ones for optoelectronic applications. Zero-dimensional colloidal semiconductor nanocrystals, known as
quantum dots (QDs), attract immense attention in the field of photonics due to their size-dependent tunable optical
By combining these two types of nanomaterials together, we demonstrate the role of graphene as an efficient
charge transfer medium from- and to II-VI quantum dots. The optical excitation of II-VI quantum dots dispersed on
single layer graphene results in an electron transfer from the nanocrystals to graphene. This is evidenced from
photoluminescence imaging and confirmed by the electrical measurements on QDs-decorated single layer graphene field
effect transistors (SLG-FET). In the second part of this paper we demonstrate an efficient hole injection from graphene
into QDs-layered nanocrystalline structures and the operation of the corresponding graphene-based quantum dot light
emitting diodes (QD-LED). We also benchmark graphene vs. indium-tin-oxide (ITO) based QD-LEDs in terms of device
electroluminescence intensity performance. Our experimental results show better hole injection efficiency for graphenebased
electrode at current densities as high as 200 mA/cm<sup>2</sup> and suggest single layer graphene as a strong candidate to
replace ITO in QD-LED technology.
MOSFET analyzer is developed to extract most important parameters of transistors. Instead of routine DC transfer and output characteristics, analyzer provides an evaluation of interface states density by applying charge pumping technique. There are two features that outperform the analyzer among similar products of other vendors. It is compact (100 × 80 × 50 mm<sup>3</sup> in dimensions) and lightweight (< 200 gram) instrument with ultra low power supply (< 2.5 W). The analyzer operates under control of IBM PC by means of USB interface that simultaneously provides power supply. Owing to the USB-compatible microcontroller as the basic element, designed analyzer offers cost-effective solution for diverse applications. The enclosed software runs under Windows 98/2000/XP operating systems, it has convenient graphical interface simplifying measurements for untrained user. Operational characteristics of analyzer are as follows: gate and drain output voltage within limits of ±10V; measuring current range of 1pA ÷ 10 mA; lowest limit of interface states density characterization of ~10<sup>9</sup> cm<sup>-2</sup> • eV<sup>-1</sup>. The instrument was designed on the base of component parts from CYPRESS and ANALOG DEVICES (USA).