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Graphene: A new material for electronics, Part 4

Graphene: A new material for electronics, Part 3 of this blog series describes the great potential of graphene as a substrate for wearable applications. This special material offers more possibilities in high innovation applications for electronics technology: the light-on-chip application is, for instance, a perfect example of such a field of research that could be powered by the utilization of graphene material as a basic building material for high speed integrated circuits. A first option might be the light-on-chip application on a silicon substrate; this solution requires the utilization of some optical couplers that are used as interfaces between the optical guides and the metal “vias” inside the structure of the PC board containing the light-on-chip electronic circuit. Tthis may create a loss of energy due to the optical coupling conversion process and it might result in a small loss of efficiency that could be avoided by utilizing a material that allows the conduction of light without such losses in efficiency; enter graphene, which has an exceptional capability for transmittance of light: (see Figure 1):

“The research suggests graphene could be a very effective material for collecting solar energy, Jarillo-Herrero says, because it responds to a broad range of wavelengths; typical photovoltaic materials are limited to specific frequencies, or colors, of light.” (Source: MIT)

Figure 1

The transmittance of graphene 3 nm material compared with glass transmittance
(Source: MIT/MTL Center for Graphene Devices and 2D Systems)

The transmittance of graphene 3 nm material compared with glass transmittance (Source: MIT/MTL Center for Graphene Devices and 2D Systems)

Graphene material has the potential to turn the light energy into electrical power, as it is demonstrated by the experiments conducted in collaboration between the EPFL, the Aarhus University and the ELETTRA research center:

“The scientists used “doped” samples of graphene, which means that they added or subtracted electrons from it by chemical means. The experiment revealed that, when doped graphene absorbs a single photon, this can excite several electrons and do so proportionally to the degree of doping. The photon excites an electron, which then rapidly “falls” back down to its ground state of energy. As it does so, the “fall” excites two more electrons on average as a knock-on effect. “This indicates that a photovoltaic device using doped graphene could show significant efficiency in converting light to electricity”, says Marco Grioni.” (Source: Central Laser Facility)

Figure 2

The properties of graphene material when interacting with light 
 (Source: Science & Technology Facilities Council - Central Laser Facility)

The properties of graphene material when interacting with light (Source: Science & Technology Facilities Council – Central Laser Facility)

Electronics technology has the potential to effectively process a light beam because there are innovative ICs able to convert light energy into an electric signal. An example of an IC that is utilized to detect the level of light is shown in the following Figures 3-7:

Figure 3

Light-to-frequency converter block diagram(Source Hamamatsu.com)

Light-to-frequency converter block diagram(Source Hamamatsu.com)

Figure 4

Example of a connection to a microcontroller(Source Hamamatsu.com)

Example of a connection to a microcontroller(Source Hamamatsu.com)

Figure 5

Spectral response(Source Hamamatsu.com)

Spectral response(Source Hamamatsu.com)

Figure 6

Output frequency vs. illuminance(Source Hamamatsu.com)

Output frequency vs. illuminance(Source Hamamatsu.com)

Figure 7

Output waveform example(Source Hamamatsu.com)

Output waveform example(Source Hamamatsu.com)

Graphene material holds promise to become a key substrate for light-on-chip applications. Do you think it will become largely adopted? Do you think that this material could be a good solution for guaranteeing high efficiency in light-on-chip applications?

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