At a particular doping level the mobility of electrons in Nt

At a particular doping level, the mobility of electrons in N-type silicon is mu_n = 1100 cm^2/Vs. If a voltage difference of 5 V is applied along the length of a 500 mum long silicon element, how long does it take for an average electron to traverse the full length of the element, in units of nanoseconds? (the answer should tell you something about why the design of high speed microprocessors requires extremely short length scales)

Solution

The design of the high speed microprocessors uses short length scales, this obnsevation can be explain with the help of Dennard scaling, which says that the amount of power required to run the transistors in a specific unit volume stays constant despite increasing their numbers such that the voltage and current scale with length , yet this observation is no longer becoming valid as transistors are going small.