DISPOSITIVOS ELECTRÓNICOS
EJERCICIOS
1. Durante el proceso de la obtención de un diodo, la cantidad de donadores se convierte en los portadores
mayoritarios para la región N, similarmente ocurre con la cantidad de Aceptores para la región P. Si se han
aplicado 1016 donadores por cm3 y 1017 aceptores por cm3, determine
a) la resistividad del diodo (sin tomar en cuenta que la movilidad disminuye)
b) el voltaje de unión
c) Si el diodo está polarizado directamente y conduce una corriente de 0.1mA, determine la resistencia del
diodo
2. Las resistividades de los dos lados de un diodo de silicio de unión tienen los valores siguientes: 2 -cm
de lado p y 1 del lado N. Calcule el valor del voltaje integral. (The built-in potential barrier is Vbi)
3. Los parámetros de una unión pn uniformemente dopada de Silicio son VT = 26 mV, T = 25°C, Na =
1x1016 cm−3 , and Nd = 2*1015 cm−3 . Encuentre (a) el voltaje de unión y (b) el ancho de la RCE W
4. Los parámetros de una unión uniformemente dopada para el Silicio semiconductor son VT = 26 mV,
T = 25°C, Na = 1*1012 cm−3, and Nd = 1016 cm−3. Find (a) Vbi (b) xn and , (c) xp the depletion width W,
5. Calcule la concentración de portadores intrínseca en silicio y germanio (a) T = 100K, (b) T = 300K, y (c)
T = 500K.
6. Silicon is doped with 5 × 1016 arsenic atoms/cm3. (a) Is the material n- or p-type? (b) Calculate the
electron and hole concentrations at T = 300K. (c) Repeat part (b) for T = 350K.
7. The electron concentration in silicon at T = 300K is no = 5 × 1015 cm−3 . (a) Determine the hole
concentration. (b) Is the material n-type or p-type? (c) What is the impurity doping concentration?
8. (a) The applied electric field in p-type silicon is E = 10 V/cm. The semiconductor conductivity is σ = 1.5
(Ω–cm)−1 and the cross-sectional area is A = 10−5 cm2. Determine the drift current. (b) The cross-sectional area of
a semiconductor is A = 2 × 10−4 cm2 and the resistivity is ρ = 0.4 (Ω –cm). If the drift current is I = 1.2 mA, what
applied electric field must be applied?
9. A drift current density of 120 A/cm2 is established in n-type silicon with an applied electric field of 18
V/cm. If the electron and hole mobilities are μn = 1250 cm2/V–s and μp = 450 cm2/V–s, respectively, determine
the required doping concentration.
10. An n-type silicon material has a resistivity of ρ = 0.65 Ω–cm. (a) If the electron mobility is μn = 1250
cm2/V–s, what is the concentration of donor atoms? (b) Determine the required electric field to establish a drift
current density of J = 160 A/cm2.
11. (a) The required conductivity of a silicon material must be σ = 1.5 (Ω-cm)−1. If μn = 1000 cm2/V–s and μp
= 375 cm2/V–s, what concentration of donor atoms must be added? (b) The required conductivity of a silicon
material must be σ = 0.8 (Ω –cm)−1. If μn = 1200 cm2/V–s and μp = 400 cm2/V–s, what concentration of acceptor
atoms must be added?
12. (a) Determine the built-in potential barrier Vbi in a silicon pn junction for (i) Nd = Na = 5 × 1015 cm−3; (ii)
Nd = 5 × 1017 cm−3 and Na = 1015 cm−3; (iii) Na = Nd = 1018 cm−3 .
13. Consider a silicon pn junction. The n-region is doped to a value of Nd = 1016 cm−3. The built-in potential
barrier is to be Vbi = 0.712 V. Determine the required p-type doping concentration.
