Evaluation of surface roughness and nanostructure of indium tin oxide (ITO) films by atomic force microscopy

Abstract

Indium tin oxide was deposited on a glass (soda lime glass) by radiofrequency sputtering system at different sputtering gas (argon/oxygen 90/10%) pressures (20-34 mTorr) at room temperature. The sputtering rate was affected by the sputtering gas pressure. The optimum sputtering gas pressure was found to be 27 mTorr. The samples at different thicknesses (168, 300, 400, 425, 475, 500 and 630 nm) were deposited on the substrate. Transparency, electrical conductivity and surface roughness of the films were characterized. The samples were annealed at 350, 400 and 450 degrees C to evaluate annealing process effects on the concerned parameters and, therefore, the above-mentioned measurements were repeated again. The films exhibited reasonable optical transmittance and electrical conductivity and greatly improved after annealing. The characterization was focused on the scanning of the film surfaces before and after annealing, which has a prominent effect on the optical properties of the films. Film surfaces were scanned by scanning probe microscopy in contact atomic force mode. The most consideration was devoted to image analysis.

Fabrication of highly conductive graphene/ITO transparent bi-film through CVD and organic additives-free sol-gel techniques

“…So the surface carrier density improvement through electron doping from ITO and the carrier mobility improvement from graphene facilitate higher conductivity or lower sheet resistance to bi-film, when compared with the individual ITO. ITO film obtained from this study reveals high surface root mean squared (RMS) roughness of about 14.398 nm and mean roughness of 12.522 nm that comparatively much higher than reported roughness values of ITO from other synthesis method such as radiofrequency (RF) magnetron sputtering 57 – 59 . Graphene/ITO bi-film with surface RMS roughness of approximately 9.387 nm and mean roughness of 7.322 nm, indicating that surface roughness of ITO film can reduce by coating graphene on it (see Supplementary Fig.…”

“…Additional resistivity is induced due to diffuse scattering of conduction electrons on the rough surface, and effect of surface roughness on electron scattering increases with increase of surface roughness. Conduction electrons impact each other during transferring and this acts as a barrier for free electron movement due to the effect of surface roughness scattering 57 . Effect of surface roughness on electron transfer can be explained in the following ways.…”

“…Surface roughness changes the thickness of the film, introducing external variations in the sub-band energy, as well as fluctuations in the wave function shape 56 . Moreover, the Born approximations can be used to express the conductivity of film when surface roughness contributes to electron scattering 57 . In the framework of this theory, surface roughness scattering is becoming more critical due to rapid variation of film thickness and resulting in reduction of electrical conductivity 55 .…”

Electric-Double-Layer-Modulation Microscopy

“…1(e)]. The sharp boundaries confining these grains are indicative of the crystallographic origin of their formation, attributed to the stress release in the deposited layer during the annealing of ITO [22,23]. We can use the fairly homogeneous size distribution of these grains on the ITO rough regions, and the straight boundaries of these regions, to distinguish between ITO grains and other particles or contamination that resides on the surface.…”

Mechanism by which ma-xing-shi-gan-tang inhibits the entry of influenza virus

“…The square root of distribution of surface height is defined as Rrms. P-v is peak-to-valley height roughness, which is the difference between the maximum and minimum distance on the surface (Hsieh et al, 2008;Kavei et al, 2008;Zhang et al, 2009). …”