ECE 440
Homework IX Due: Monday, November 03, 2008
Fall 2008
1. A p+-n silicon diode (Vo = 0.956 volts) has a donor doping of 10 /cm and an nregion width = 1 m. Does it break down by avalanche or punchthrough? What if the 16 3 doping is only 10 /cm ? Refe
ECE 440
Homework V Due: Friday, October 09, 2009
Fall 2009
Please write your name and net ID on your homework. Show all work leading to your answer. 1. The acceptor profile of a silicon sample is shown below. Assume that the majority carrier mobility can
ECE 440
Homework VII Solutions
Spring 2008
1. Consider a silicon sample at 300 K. Assume that the difference of hole concentration varies linearly with distance. At x=0, the hole concentration is p(0). At x=10 m, the hole concentration is p(10 m)= 5x1014/
ECE 440 Due: Friday, September 25, 2009
Homework IV
Fall 2009
Print your name and netid legibly. Show all work leading to your answer clearly and neatly. Staple multiple pages. 1. A Si bar is 0.2 cm long and 200 m2 in cross-sectional area. Find the curren
ECE 440
Homework V Due: Monday, September 29, 2008
Fall 2008
1. How long does it take an average electron to drift 0.2 mm in (a) pure Si and (b) Si doped with 6x1016/cm3 donors at an electric field of 100 V/cm? Repeat for 105 V/cm. Assume that the electro
ECE 440
Homework II Solutions
Spring 2008
1. (a) A GaAs semiconductor crystal is doped with silicon atoms. If all silicon atoms displace Ga atoms, does the crystal become an n-type or p-type material? Why? What if 3/4 silicon atoms displace Ga atoms while
ECE 440
Homework IV Due: Monday, September 22, 2008
Fall 2008
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 ce
ECE 440
Solution Due: Wednesday, September 2, 2009
Fall 2009
1. In this problem, we will be partly using a web-based simulations that are contained within the NanoHUB website (a NSF sponsored education and research resource), which can be found at: https:
ECE 440
Homework V Solutions
Spring 2008
1. (a) A Si bar 0.1 cm long and 100 m2 in cross-sectional area is doped with 5x1016/cm3 arsenic atoms. Find the current at 300 K with 10 V applied across the length. To find current, use Ohms law:
Since we already
ECE 440
Homework VI
Spring 2008
1. (a) Construct a semilogarithmic plot such as Fig. 4-7 for Si doped with 4x1016/cm3 donors and having 4x1014 EHP/cm3 created uniformly at t = 0. Assume that n= p = 2 s. How much time is needed before the minority carrier
ECE 440
Homework XII Due: Monday, December 01, 2008
Fall 2008
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 problem is designed to
ECE 440 11.
Homework I Solutions
Spring 2008
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 maximum fractions of the
ECE 440
HW1 Solutions
Summer 2009 Thu, Jun 18, 2009
1. Beginning with a sketch of a fcc lattice, add atoms at (1/4, 1/4, 1/4) from each fcc atom to obtain the diamond lattice. Show that only four added atoms in Fig. 18a appear in the diamond unit cell. Ho
ECE 440
HW2 Solutions
Summer 2009 Thu, June 25, 2009
1. An InP semiconductor crystal is doped with tin atoms. If the tin displaces indium atoms, does the crystal become an n-type or p-type material? Why? InP is a III V compound semiconductor. Tin (Sn) is
ECE 440
HW3 Solutions
Summer 2009 Tue, Jun 30, 2009
1. Calculate both the electron and hole concentrations for a germanium sample doped 16 3 with 2x10 arsenic atoms/cm (a) at room temperature (b) at 450 K. Doping germanium with arsenic will make the sampl
ECE 440
HW4 Solutions
Summer 2009 Thu, Jul 02, 2009
1. (a) A Si bar 0.1 cm long and 100 m2 in cross-sectional area is doped with 1x1017/cm3 arsenic. Find the current at 300 K with 10 V applied across the length. To find current, use Ohms law. Since we alr
ECE 440
HW5 Solutions
Summer 2009 Tue, Jul 07, 2009
1. Consider a silicon sample at 300 K. Assume that the hole concentration varies linearly with distance. At x=0, the hole concentration is p(0). At x=10 m, the hole concentration is p(10 m)= 5x1014/cm3.
ECE 440
October 1, 2009
First Hour Examination
Name:_Section_
1) [5points] The energy band gap of silicon is around 1.12eV at 300K. What is the probability
for the conduction band edge to be occupied by electrons in intrinsic silicon (Fermi function:
f(E)
ECE 440
Homework VIII Due: Monday, October 27, 2008
Fall 2008
1. An abrupt Si p-n junction has the following properties at 300 K: p-side Na = 3x1017/cm3 n = 0.1 s p = 180 cm2/V-s n = 540 cm2/V-s n-side Nd = 6x1015/cm3 p = 10 s n = 1160 cm2/V-s p = 420 cm2
ECE 440
Homework VII Due: Monday, October 20, 2008
Fall 2008
1. An abrupt Si p-n junction has Na = 6x1016/cm3 on the p-side and Nd = 2x1017/cm3 on the nside. (a) Calculate the Fermi level positions at 300 K in the p and n regions. P region: (1) Ei Ef = N
ECE 440
Homework VI Due: Wednesday, October 08, 2008
Fall 2008
1. Consider a silicon sample at 300 K. Assume that the electron concentration varies linearly with distance. At x=0, the electron concentration is n(0). At x=10 m, the electron concentration i
ECE 440
Homework IV Due: Monday, September 22, 2008
Fall 2008
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 ce
ECE 440
Homework III Due: Monday, September 15, 2008
Fall 2008
1. (a) A GaAs semiconductor crystal is doped with carbon atoms. If the carbon atoms displace arsenic atoms, does the crystal become an n-type or p-type material? Why? (b) For a nonstoichiometr
ECE 440
HW9 Solutions
Summer 2009 Wed, Aug 05, 2009
1. Redraw Fig. 6-12 for the p-channel (n-type substrate) case. Also include schematic drawings showing the electric circuit and contact configurations.
1
ECE 440
HW9 Solutions
Summer 2009 Wed, Aug 05, 20
ECE 440
HW8 Solutions
Summer 2009 Thu, July 30, 2009
1. Redraw Fig. 7-3 for an n -p-n transistor, and explain the various components of carrier flow and current directions.
+
1. Electrons injected from the emitter but are lost to recombination with holes
ECE 440
HW6 Solutions
17 3
Summer 2009 Thu, Jul 16, 2009
15 3
1.
An abrupt Si p-n junction has A = 3 x 10 /cm on the p-side and D = 2x10 /cm on the n-side. (a) Calculate the Fermi level positions in the p and n regions at 300 K. P region:
N region:
(b) Dr
ECE 440
Homework VIII Solutions
Spring 2008
1. An abrupt Si p-n junction is formed by alloying a uniformly doped n-type silicon bar of which Nd = 4x1016/cm3. During the alloying process, a uniform counter doping of acceptors of Na = 1.5x1017/cm3 is introd
ECE 440
Homework IX Solution to be posted by Wednesday, March 12, 2008
Spring 2008
1. An abrupt Si p-n junction has the following properties at 300 K: p-side n-side Na = 1x1017/cm3 n = 1 s p = 220 cm2/V-s n = 700 cm2/V-s Nd = 1x1016/cm3 p = 10 s n = 1080