Extrinsic semiconductors Carriers in doped semiconductors sa

Extrinsic semiconductors: Carriers in doped semiconductors satisfy Fermi-Dirac statistics. Using the Boltzmann approximation (E>> E_F) to the Fermi-Dirac statistics, the carrier concentrations for an extrinsic semiconductor are given (at relatively low temperatures) by: n = (1/2 N_dN_vc)^1/2 exp(-E_d/2k_B T) where N_d = donor concentration E_d = donor level, measured down from E_CB p = (1/2 N_a N_v)^1/2 exp(-E_a/2k_B T) where N_a =acceptor concentration E_a = accepter level, measured up from E_VB Assuming these equations apply to room temperature, and using the Boltzmann approximation. Calculate the electron concentration, hole concentration, resistivity, and the Fermi level for Si at room temperature (T = 300K) with the following doping. Also state whether it will be n-type or p-type. 1.4 times 10^16 Boron/cm_3 8 times 10^16 Arsenic/cm^3 b. The Boltzmann approximation, E>>E_F assumes that the relevant energy that you are computing is at least 3k_B T away from the Fermi level (note that the expression E>>E_F is valid for p-type when we consider the hole energies as increasing downward. Alternatively, consider the absolute value of the difference). Discuss the validity of the Boltzmann approximation at room temperature for the given doping above. rho = i/sigma = (nq mu)^-1 or rho = 1/sigma =(pq mu)^-1 for silicon at T = 300K, mu_P=1450 cm^2 V^1 s^1 and mu_P=505 cm^2 V^1 s^1. E^B (from VB) = 0.045 eV, E_n(from CB) = 1.075 eV E_As(from VB) = 1.066 eV, E_As(from CB) = 0.054 eV

Solution

Transmission lines are sets of wires, called conductors, that carryelectric power from generating plants to the substations that deliver power to customers. At a generating plant, electric power is “stepped up” to several thousand volts by a transformer and delivered to thetransmission line.