ECE 340
Homework VII
Fall 2003
Due: Friday, October 03, 2003
14
17
1. An intrinsic Si sample is doped with donors symmetrically about xo= 2 m such that Nd (x) = 10 + 10
9
2
exp [-10 (x-xo) ] for 1 m x 3m, where x is expressed in cm.
2
(a)
Assuming a unifo
ECE 340
Homework XVII
Due: Friday, December 05, 2003
Fall 2003
1. A lightly-doped-drain (LDD) structure is incorporated in a MOSFET. To fabricate such a structure, a
heavy diffusion or implantation is first used to increase the doping in the drain region.
ECE 340
Homework XVI
Fall 2003
Due: Friday, November 21, 2003
(30 points total)
+
16
3
1. An n -polysilicon-gate p-channel MOS transistor is made on an n-type Si substrate with Nd = 5x10 /cm .
11
2
The SiO2 thickness is 100 in the gate region, and the eff
ECE 340
Homework XV
Fall 2003
Due: Monday, November 17, 2003
1. Other than aluminum, polysilicon is another common gate metal for the MOS structure in silicon. By
incorporating heavy doping during chemical vapor deposition of polysilicon one can greatly i
ECE 340
Homework XIV
Fall 2003
Due: Wednesday, November 12, 2003
(30 points total)
1.
Field-effect transistors employ a mechanism different from that of BJT to control the output current by changing the charge
density in the active region. The following p
ECE 340
Homework XIII
Fall 2003
Due: Wednesday, November 05, 2003
(solutions, 40 points total)
+
1. Redraw Fig. 7-3 for an n -p-n transistor, and explain the various components of carrier flow and current
directions.
2. Sketch the energy band diagram for
ECE 340
Homework XII
Due: Wednesday, October 29, 2003
(20 points total)
Fall 2003
1. A Schottky barrier is formed between a metal having a work function of 4.2 eV and p-type Si (electron
affinity = 4 eV). The acceptor doping in the Si is 5x1017/cm3. (a) D
ECE 340
Homework XI
Fall 2003
Due: Friday, October 24, 2003
+
1. A p -n silicon diode (Vo = 0.956 volts) has a donor doping of 1017/cm3 and an n-region width = 1
m. Does it break down by avalanche or punchthrough? What if the doping is only 1016/cm3? Refe
ECE 340
Homework X
Fall 2003
Due: Monday, October 20, 2003
(30 points total)
1. An abrupt Si p-n junction has the following properties at 300 K:
p-side
Na = 2x1017/cm3
n = 0.1 s
p = 190 cm2/V-s
n = 600 cm2/V-s
A = 10-3cm2
n-side
Nd = 4x1015/cm3
p = 10 s
ECE 340
Homework IX
Fall 2003
Due: Wednesday, October 15, 2000
(20 points total)
1. Consider the following Si p-n junctions operating at 300 K.
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19
3
14
15
(a) Using Eq. (5-8), calculate the contact potential Vo for Na = 5x10 and 10 /cm , with Nd = 10 ,
ECE 340
Homework VIII
Due: Friday, October 10, 2003
16
3
Fall 2003
17
3
1. An abrupt Si p-n junction has Na = 7x10 /cm on the p-side and Nd = 2x10 /cm on the n-side.
(a)
Calculate the Fermi level positions at 300 K in the p and n regions.
(b)
Draw an equi
ECE 340
Homework VI
Fall 2003
Due: Monday, September 29, 2003
16
3
1. How long does it take an average electron to drift 0.1 mm in (a) pure Si and (b) Si doped with 6x10 /cm
5
donors at an electric field of 100 V/cm? Repeat for 10 V/cm. Assume that the el
ECE 340
Homework V
Fall 2003
Due: Wednesday, September 24, 2003
Solution: 30 points total
16
3
21
3
1. An p-type Si sample with Na = 2x10 /cm is steadily illuminated such that gop= 10 EHP/cm -s. If n=
p =1 s for the excitation, calculate the separation in
ECE 340
Homework IV
Fall 2003
Due: Monday, September 22, 2003
17
3
13
3
1. A compensated germanium sample is doped with 1x10 /cm acceptors and 5x10 /cm donors. (a) What
is the electron and hole concentration respectively at room temperature under equilibr
ECE 340
Homework III
Fall 2003
Due: Monday, September 15, 2003
1. In practice we assume that the intrinsic Fermi level, Ei, coincides with the center of the band gap. In
reality it is not true. Derive an expression relating the intrinsic level Ei to the c
ECE 340
Homework II
Fall 2003
Due: Wednesday, September 10, 2003
1. (a) An InP semiconductor crystal is doped with tin atoms. If the tin atoms displace indium
atoms, does the crystal become an n-type or p-type material? Why?
(b) For a nonstoichiometric Ga
ECE 340
Homework I
Fall 2003
Due: Friday, September 05, 2003
1. How many atoms are found inside a unit cell of a simple cubic (sc), body-centered cubic
(bcc), face-centered cubic (fcc), diamond structure, and zinc-blende structure crystal? Find
the maximu
ECE 340
Homework XVIII
Fall 2003
Due: Wednesday, December 10, 2003
1. Refer to Fig. 1-13. Assuming the lattice constant varies linearly with composition x for a ternary alloy,
what composition of GaSb1-xAsx is lattice-matched to InP? What composition of I