固態電子元件導論 第四章習題
Introduction to Solid-State Electronic Devices Homework #4
指導教授: 張廖貴術 教授
繳交期限: 4/1
1.
(a) The maximum intrinsic carrier concentration in a silicon device must be limited to 5 x 1012
cm-3. Assume Eg = 1.12 eV. Determine the maximum temperature allowed for the device.
2.
(a) Determine the values of n0 and p0 in GaAs at T = 300 K if EF ‒ EV = 0.25 eV.
(b) Assuming the value of p0 in part (a) remains constant, determine the value of EF ‒ EV and
n0 at T = 400 K.
3.
Assume that silicon (Si), germanium (Ge), and gallium arsenide (GaAs) each have dopant
concentrations of Nd = 2 x 1013 cm-3 and Na = 3.5 x 1013 cm-3 at T = 300 K. For each of the
three materials: (a) Is this material n-type or p-type? (b) Calculate n0 and p0.
4.
For a particular semiconductor, Eg = 1.50 eV, mp* = 10 mn*, T = 300 K, and ni = 1 x 105 cm-3.
(a) Determine the position of the intrinsic Fermi energy level with respect to the center of the
bandgap. (b) Impurity atoms are added so that the Fermi energy level is 0.45 eV below the
center of the bandgap. (i) Are acceptor or donor atoms added? (ii) What is the concentration
of impurity atoms added?
5.
GaAs at T = 300 K is doped with donor impurity atoms at a concentration of Nd = 1 x 1015
cm-3. (a) Determine EC – EF. (b) Calculate the concentration of additional donor impurity
atoms that must be added to move the Fermi energy level a distance kT closer to the
conduction band edge.