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This relative alignment of the energy bands at such semiconductor heterojunctions is called the Band offset. The band offsets can be determined by both intrinsic properties, that is, determined by properties of the bulk materials, as well as non-intrinsic properties, namely, specific properties of the interface.
The van der Pauw Method is a technique commonly used to measure the resistivity and the Hall coefficient of a sample. Its strength lies in its ability to accurately measure the properties of a sample of any arbitrary shape, as long as the sample is approximately two-dimensional (i.e. it is much thinner than it is wide), solid (no holes), and the electrodes are placed on its perimeter.
This is an advantage, because sheet resistance of 1 Ω could be taken out of context and misinterpreted as bulk resistance of 1 ohm, whereas sheet resistance of 1 Ω/sq cannot thus be misinterpreted. The reason for the name "ohms per square" is that a square sheet with sheet resistance 10 ohm/square has an actual resistance of 10 ohm ...
For semiconductor alloys it may be necessary to use Vegard's law to calculate these values. Once the relative positions of the conduction and valence bands for both semiconductors are known, Anderson's rule allows the calculation of the band offsets of both the valence band ( Δ E v {\displaystyle \Delta E_{\rm {v}}} ) and the conduction band ...
The Shockley diode equation relates the diode current of a p-n junction diode to the diode voltage .This relationship is the diode I-V characteristic: = (), where is the saturation current or scale current of the diode (the magnitude of the current that flows for negative in excess of a few , typically 10 −12 A).
The former component can be described with the formula , whereas represents the sheet resistance of the semiconductor substrate and the width of the metal pads. The other component that contributes to the total resistance is denoted by 2 R C {\displaystyle 2R_{C}} because when two adjacent pads are characterized two identical metallized areas ...
This formula involves the same approximations mentioned above. Therefore, if a plot of h ν {\displaystyle h\nu } versus α 2 {\displaystyle \alpha ^{2}} forms a straight line, it can normally be inferred that there is a direct band gap, measurable by extrapolating the straight line to the α = 0 {\displaystyle \alpha =0} axis.
Here is the effective mass of the electrons in that particular semiconductor, and the quantity is the difference in energy between the conduction band and the Fermi level, which is half the band gap, : = ()