Effect Of Capping Layer Thickness Research Articles

Graphene/Graphene Oxide-Based Ultrasensitive Surface Plasmon Resonance Biosensor

Surface plasmon resonance (SPR)-based biosensing is an accurate and sensitive technique used to evaluate the biomolecular interactions in real time in a label-free environment. Several new approaches have been proposed to improve the sensitivity of SPR sensors. The development of sensing surfaces can significantly improve the performance of biosensors; graphene and graphene oxide (GO) offer several advantages due to their extraordinary optical and structural properties. In this paper, the SPR biosensor structure based on graphene and GO linking layers are suggested. For proposed configurations, the features and characteristics such as reflectivity and sensitivity using the finite element analysis (FEA) model are discussed and compared with results from N-layer model. The effect of cap layer thickness in the sensitivity of the SPR biosensor has been calculated. Computational results show that the proposed graphene and GO-based SPR biosensor have more than two and four times greater sensitivity than the conventional gold film-based SPR sensor respectively due to their better adsorption of biomolecules.

Strain recovery in partially relaxed In0.2Ga0.8As/GaAs single quantum wells with increasing GaAs cap layer thickness

The effect of cap layer thickness on residual strain in partially relaxed, 250 AA thick In0.2Ga0.8As/GaAs single quantum well structures was examined by photoluminescence, transmission electron microscopy and high-resolution x-ray diffraction. When the cap layer thickness increased from 50 to 5000 AA, the residual strain increased from 0.88% to the misfit value of 1.4%. As a consequence the cap layer thickness should be taken as a parameter, along with misfit and growth temperature, to determine critical layer thickness in lattice-mismatched single quantum well structures.