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ECSE-2210 Microelectronics Technology
Fall 2005 Homework 2
Reading Assignment: Pages 40-74. Late submissions will be penalized. Hand in your solutions
during the class.
1. A Si sample is doped such that it has 1017 cm-3 electrons in its conduction band
(i.e. n = 1017 cm-3) at both 300 K and 200 K. Calculate the hole concentrations at 300 K and
200 K. Figure 2.20 has the ni values for various temperatures.
2. (Problem 2.17 in text) Determine the equilibrium electron and hole concentrations inside a
uniformly doped sample of Si under the following conditions:
(a) T = 300 K, NA << ND, ND = 1015 cm-3.
(b) T = 300 K, ND << NA , NA = 1016 cm-3.
(c) NA = 9 × 1015 cm-3, ND = 1016 cm-3, T = 300 K.
(d) ND = 1014 cm-3, T = 450 K.
(e) ND = 1014 cm-3, T = 650 K.
3. (Problem 2.18 in text) For each of the conditions specified in Problem 2, determine the
position of Ei , Compute EF - Ei , and draw a carefully dimensioned energy band diagram for
the Si sample. Note: EG (Si) = 1.08 eV at 450 K and 1.015 eV at 650 K. Also, read exercise
2.4 in text (page 55).