Equiano’s experience on a slave ship introduced him to a type of slavery that seemed worse than other forms of slavery he had known:

Dr. Feimster suggests we need to ask ‘different questions’ to get a fuller understanding of what violence looked like during the Civil War:

Dr. Cornel West and Tavis Smiley both argue that Malcolm X demonstrated far more courage than Dr. King:  

Question 4: (25 points) For a silicon pn junction at 300 K with the following parameters: Na = Nd = 1×1015 cm–3, e = 1.60×10–19 C, ni = 1.5×1010 cm–3, Dn = 25 cm2/s, Dp = 10 cm2/s, and tpo = tno = 5×10–7 s. Determine: The total reverse saturation current density at 300 K. (5 points) The total reverse current is composed of the reverse current of electrons Jsn and that of holes Jsp. Determine the ratio of Jsn to Jsp, Jsn/Jsp. (6 points) All the parameters above are more difficult to control except the doping concentration. If you keep one doping concentration constant, say you keep Na constant at 1×1015 cm–3, what is the other doping concentration Nd to increase the Jsn/Jsp ratio to 3? (7 points) If you want to operate this pn junction at 400 K and keep the total reverse saturation current the same as in part (a), what would be the doping concentration if you also keep Na = Nd? ni = 2.38×1012 cm–3 at 400 K and all other parameters are independent of temperature. (7 points)

Question 1 (30 points) Gallium arsenide (GaAs) has a zincblende structure. Its lattice constant is 5.65 Å (1 Å = 1×10–8 cm). (a) How many arsenic atoms the unit cell below contains? Please show your calculation. How many gallium atoms does the unit cell contain? (8 points) (b) On its (100), what is the atomic density of arsenic atoms? That is, how many arsenic atoms are there on a 1-cm2 area? Show your procedure to obtain this number. The unit should be atoms/cm2. (7 points) (c) Determine the atomic density of gallium arsenide in atoms/cm3, that is, the total number of gallium and arsenic atoms in a 1-cm3 volume. (7 points) (d) If the atomic mass unit (AMU) of gallium and arsenic atoms are 69.7 and 74.9, respectively (1 AMU = 1.6605 × 10–24 grams), what is the density of gallium arsenide in grams/cm3. (8 points)

Question 3: (25 points) Consider a uniformly doped silicon pn junction with doping concentrations Na = 5×1015 cm–3 and Nd = 1×1016 cm–3. Determine: Vbi at T = 300 K. (5 points) xn at zero bias V = 0 V. (7 points) xn at reverse bias VR = 2 V. (5 points) The junction capacitance if the junction area is 1×10–4 cm2 and at zero bias V = 0 V and at reverse bias VR = 2 V. (8 points) e = 1.60×10–19 C, k = 8.62×10–5 eV/K, ni = 1.5×1010 cm–3 at 300 K,

Question 1: (25 points) Consider a n-type silicon wafer with a donor concentration of Nd = 1×1015 atoms/cm3 and Na = 0. Take the bandgap of silicon as 1.12 eV, NC = 2.80×1019 cm–3, NV = 1.04×1019 cm–3. To simplify the calculation, you can assume that these three values are all temperature independent. For the same reason, let’s assume that the electrons and holes obey the Boltzmann distribution. The Boltzmann constant is 1.38×10–23 J/K or 8.62×10–5 eV/K, and 1 eV = 1.60×10–19 J. Determine the temperature at which the intrinsic carrier concentrations is equal to the extrinsic electron concentration. (10 points) Determine the Fermi energy EF in EC – EF at 300 K for the n-type silicon assuming complete ionization of the donors. (5 points) Calculate the electron and hole concentrations at 700 K. You need the result from part (a) to determine which equations to use for this temperature. (10 points)

What is the 2’s complement representation of the 8-bit binary number 10110100?

Which of the following statements about loops in C++ is true?

A good business plan leads to a successful company when the entrepreneur and management team