The forbidden energy gap between the valence band (VB) and the conduction band (CB) of a material, which needs to be overcome to produce free charge carriers. 

The bandgap determination is accomplished using the Tauc plots, where (αhν)n is plotted as a function of the energy hν (h- Planck’s constant, ν- energy frequency) for a given point in the library. 

The power n is established based on the type of bandgap the material has. For a direct bandgap n=2 and for an indirect bandgap n=0.5. The obtained graph, from the (αhν)n vs. hν plot, contains a linear area to which a straight line is fitted and extrapolated to the energy (x) axis. 

The point where the linear fit and the x-axis intercept is the bandgap of the material,

Over 100,000 band gaps were calculated from optical scans and thickness measurements for over 600 libraries. 

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Other Combinatorial Database: Materials and Scans

MaterialsZone Catalogue

Browse using our listings engine: by challenges / by materials / by physical measurements / by instruments.

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Optical Scans

This method is used to obtain the optical properties of the material and device libraries.

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Composition Data

The EDS detector in a high-resolution scanning electron microscope (HRSEM) was used to determine the compositions

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The XRD is utilized to determine the crystalline structure and oxidation states of the different metal oxide layers we obtained.

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Current Voltage scans

In the J-V method the photocurrent is measured as a function of the photovoltage of the solar cell.

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Sheet Resistance

Sheet Resistance (SHR) is the resistance of a two-dimensional layer, for example thin film, doped semiconductor region.

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