Consider that the concentration of electrons in a semiconductor bar varies linearly from \(2\times10^{17}\text{ cm}^{-3}\) at \(x=1\ \mu\text{m}\) to \(1\times10^{16}\text{ cm}^{-3}\) at \(x=4\ \mu\text{m}\) along the \(x\)-direction. Assume that the concentration of electrons does not vary along the \(y\)- and \(z\)-directions.
Given: the mobility of electron is \(1400\ \text{cm}^2\text{V}^{-1}\text{s}^{-1}\), the thermal voltage is \(25\text{ mV}\) and the electronic charge is \(1.6\times10^{-19}\) Coulomb.
The density of electron diffusion current (in \(\text{A/mm}^2\)) is (rounded off to two decimal places).