n-type silicon is obtained by doping silicon with

The electron concentration in a sample of uniformly doped n-type silicon at 300^oK varies linearly from $$10^{17}/cm^3$$ at x = 0 to $$6\times10^{16}/cm^3$$ at x = 2 $$\mu m$$. Assume a situation that electrons are supplied to keep this concentration gradient constant with time.If electronic charge is $$1.6\times10^{-19}\;coulomb$$ and the diffusion constant $$D_n=3\;cm^2/s$$, the current density in the silicon, if no electric field is present is

An n-type silicon bar 0.1 cm long and $$100\;\mu m^2$$ in cross-sectional area has a majority carrier concentration of $$5\times10^{20}/m^3$$ and the carrier mobility is $$0.13\;\;m^2/v-s\;$$ at 300^oK. if the charge of an electron is 1.6×10^-19 coulomb, then the resistance of the bar is

At 300 K, for a diode current of 1 mA, a certain germanium diode requires a forward bias of 0.1435 V. Where as a certain silicon diode requires a forward bias of 0.718 V. Under the conditions stated above, the closest approximation of the ratio of reverse saturation current in germanium diode to that in silicon diode is