ECE344 Semiconductor Devices and Materials
M. Fischetti 201 D Marcus Hall Department of Electrical and Computer Engineering University of Massachusetts Amherst, MA 01003 Fall 2009
The crisis of Classical Mechanics
At the end of the XIX century classical p
ECE344 Practice Problems for Midterm Exam 2 November 15, 2005
1. Problem. An n-type silicon sample has a resistivity of 5 .cm at T = 300 K. Assume that the electron mobility at this temperature is 1,500 cm2 /Vs and that the mobility varies as T 3/2 . (a)
ECE344, Midterm Exam 1: Solutions October 19, 2009
1. Problem: The workfunction of a material is dened as the energy required to remove an electron from the material and is usually indicated by the Greek letter (pron: khi). The workfunction of gold is Au
ECE344: Practice questions for Midterm Exam 1: Solutions, October 13, 2009
1. Problem. a. An electron is moving with a velocity of 2 106 cm/s. Determine the electron energy in eV, its momentum, and de Broglie wavelength in nm. energy (in eV), momentum, an
Homework 7
1. Problem: (a) Consider an n-channel MOSFET with uniform channel doping with NA = 3 1017 cm3 and having an oxide 10 nm thick. Calculate the sub-threshold slope at 300 K. (b) Assume now that the Si-SiO2 interface is not ideal, but there are int
Homework 6
1. Problem: (a) Using the gures on pages 133 and 134 of the Lecture Notes, Part II, as a guide, sketch the band diagram of an MOS capacitor with an n-type Si substrate in i) accumulation, ii) at at band condition, and iii) at the onset of stron
Homework 5
1. Problem: A silicon p-n junction is formed between n-type Si doped with ND = 1017 cm3 and p-type Si doped with NA = 1016 cm3 . (a) Sketch the energy band diagram. Label all axes and all important energy levels. (b) Find nn0 , np0 , pp0 , and
Homework 4
1. Problem: Find the resistivity (in ohm-cm) for a piece of Si doped with both acceptors (NA = 1019 cm3 ) and donors (ND = 1016 cm3 ). Since the electron and hole mobilities depend on the concentration of the dopants, use the following empriric
Homework 3
1. Problem. Calculate the value of the Fermi level and sketch its position in a band diagram for the following cases: a. Ge, n-type, ND = 1017 cm3 , T = 300 K. b. Si, p-type, NA = 2 1018 cm3 , T = 450 K. c. GaAs, n-type, ND = 1018 cm3 , NA = 5
Homework 2
1. Problem. The atomic weight A of the only stable isotope of As is 75. There are two stable isotopes of Ga: One of atomic weight 69, occurring with 60.4% abundance. The second isotope has A=71, with natural abundance 39.6%. The atomic mass uni
Homework 1
1. Problem: Streetman, Sixth Ed., Problem 2.2: Show that the third Bohr postulate, Eq. (2-5) (that is, that the angular momentum p around the polar axis is an integer multiple of the reduced Planck constant h, so p = nh) is equivalent to an int
Transistors
Transistors are three-terminal devices. Essentially, they are resistors (so, devices with two terminals, say 1 and 2) whose resistance can be varied over a large range of values by means of a third terminal (say 3), as shown in the gure below.
p-n junctions
Intuitive description. What are p-n junctions? p-n junctions are formed by starting with a Si wafer (or substrate) of a given type (say: B-doped p-type, to x the ideas) and diusing or implanting impurities of opposite type (say: n-type, as
ECE344 Midterm Exam November 18, 2005
1. Problem. Consider a sample of silicon at T = 300 K. Assume that the electron concentration varies linearly from n(0) at x = 0 to 5 1014 cm3 at x = 0.01 cm. The diusion current density is measured to be jn = 0.19 A/