In a linear relationship there is a constant ratio between two parameters for example with a constant-value resistor, the relationship is R = V/I. So if you double volts you also double current.
A non-linear relationship does not show such constant ratio. For example the force F exerted by a stream (at speed v) of air on an object is F=kv2 so if we double the speed we get 4 times the force - that's non-linear!
Use this to brush up your spelling a bit!
This non applicability is due to to the method with which the conduction in the device is obtained.
A normal conductor has a stable band of conduction, so the quantity of electrons fluxing within the component is directly linked to the various conditions that are applied to it.
Once a tension is applied,the electrons all accumulate the same quantity of energy: if this is sufficient to make them jump within the conduction band then where passive element conducts electricity hijacking part of the input energy to to allow the same conduction that occurs.
In semiconductors there is a principle of conduction in function of the available electrons within the system.
The construction of these elements is subject not only to the resistivity (R=k*L/A , k→Constant of conduction) but also to a range of drugging elements.
If the quantity is not sufficient then there is no conduction, if the quantity is to much, the conduction is so high that the component burs out almost immediately.
In these components having an excess of electrons or a number of vacancies ( Technological construction ), electrons are already free to move within the component even without a proper induced tension: the appliance of a tension acts just as a KIND of field, aligning the flow of electrons within the component.
There is then the less resistivity to electron flow, and the capability of electron repulsion of the cristal elements within the semiconductors, which allows a jump prom a spot to the next at much higher speed, allowing theoretically electrical flow to be infinite ( short circuit [diode], the burning out of the component is the limit ): so resistivity is not linear but exponential.
So Ohm's law is not applicable: it doesn't consider all the electrical characteristics, contour varying, of these components.
A linear device is a component for which the system output is directly corelabile with the input, the law that such a system respects is given analytically by: y(x) = k * x , in the specific case of resistances R(k, L, A) = k * L / A ( Graphically a line ).
A non linear component is one that has an expression other than the one shown above, which can be: y(x) = k* x^2 // y(x) = k*cos(x) // y(x) = k* sin(x) // y(x) = k*e^x ( Graphically a various number of types but NOT a line ).
In the case of semiconductors resistivity we fall within the last case: R = R0 * e^(E_gap /2kb T).
As you can can see: k → R0 , x = E_gap /2kb T where E_gap is the energy gap within the conductive bands and non conductive, T is the temperature and kb is the Boltzmann constant.
Ohms Law is a linear relationship that defines resistance at a specific V and I value for any electrical/electronics device (as per Georg Ohm's 1827 definition). Ohm's law specifies linearity of a particular material characteristic. Semiconductor is nonlinear device, so not applicable in semiconductor device.
Linear device is an electrical element/device with a linear relationship between current and output voltage. Resistors are the most common example of a linear element; other examples include capacitors, inductors, and transformers.
Nonlinear device is an electrical element which does not have a linear relationship between current and voltage.
For small signal analysis Ohm's law is applicable to semiconductors. This is true because the circuit is linearized at the specific operating point.
