Evidence of Decreased Optical Absorption of Chemical Vapor Deposition Graphene Multilayers Deposited on Semiconductor Structures

Graphene absorption has a widely accepted theoretical value of 2.3% for a freestanding single layer in a wide spectral range that covers the visible spectrum. This value is also oftentimes assumed when graphene films are part of more complex structures. However, the absorption of graphene depends on the refractive indices and thicknesses of the adjacent media. In this paper, we have determined the absorption of graphene for a wide range of thicknesses of AlInP layers (a typical III–V semiconductor used in optoelectronic devices) as an example of the surrounding medium and as a function of the number of graphene layers. The resulting absorption minima within the spectrum range from 400 to 900 nm are 0.9, 2.0, and 3.0% for one, two, and three monolayers of graphene, respectively, on a 30 nm thick AlInP layer. This decrease of graphene absorption with regard to the nominal value of 2.3% can be used in the quest of a more effective design for optoelectronic devices.