Assuming dopant atoms are uniformly distributed in a silicon crystal, how far apart are these atoms when the doping concentration is (a) 10^{13 }cm^{-1}, (b) 10^{18 }cm^{-1}, and (c) 5 x 10^{20} cm^{-1}?

Consider a piece of pure silicon 100 um long with a cross sectional area of 1 um^{2}. How much current would flow through this “resistor” at room temperature in response to an applied voltage of 1 volt?

b. What is the expression for the minimum conductivity?

c. Is this value greatly different than the value calculated for intrinsic silicon at room temperature?

When a Au atopm sits on a liattice site in a silicon crystal, it can act as either a donor or an acceptor. E_{D} and E_{A} levels both exist for the Au and both are close to the middle of the Si bandgap. If a small concentration of Au is placed in an N-type silicon crystal, will the Au behave as a donor or an acceptor? Explain.

A silicon diode has doping concentrations on the N and P sides of N_{D} = 1 x 10^{19} cm^{-3 }and N_{A} = 1 x 10^{15 }cm^{-3}. Calculate the process temperature at which each of the two sides of the diode becomes intrinsic. (Intrinsic is defined as n_{i} = N_{D} or N_{A})