Electronics Devices Homework Help

1. Draw the circuit schematic for the voltage doubler, like Figure 4. Use an input signal of 1 kHz sine wave with an amplitude of 0.7 Vrms. Assume the forward threshold voltage of the diode is 0.4 V. Use Rs = 100 , RL = 10 kn. Assume CB is fully charged at steady state. 2. Calculate the peak output voltage at steady state. [A-2] 3. Calculate the expected peak-to-peak ripple voltage due to capacitor C₁ discharging. [A-3] 4. Calculate the DC value, which is given by the average value of the ripple wave. [X-1] To find this, you will have to find how much the output voltage discharges through RL. Then find the time-average of the steady-state DC signal during the charging and discharging cycles. 5. Record the values in Table 1. [T-1] 6. Sketch the input and output waveforms in steady state, showing two waves, clearly labeling all axes and marking all relevant voltage and time values. [A-4] [A-1]

Q1. Describe steps in demonstrating a III-V semiconductor laser.

Q2. After you fabricate your device, following the steps you outline in Q1, how will you test whether you have a laser or a light emitting diode?

Design an Aluminum-Si Schottky diode that fits the current-voltage characteristics of Figure 3.10, page 156 of Muller and Kamins (3rd ed. of textbook) with : Is= 8.371E-12 A, n=1.066, Area=4.2E-6 cm².

b) Graph the semilog I-V results from calculation obtained in part a). MATLAB only.

c) Show simulated I-V characteristics using PSpice/Orcad: Submit TABULATED library data used in Orcad. How does it compare with Matlab result obtained in part b). Explain any differences.

Given: λ = 152 nm ф = беV Find minimum stopping voltage (if it exists)

1) Consider the Hall Effect setup below. Find the Hall Field and associated Hall Voltage for both a positive (h+) and negative (e-) charge.

4) Consider table 2.5 (pp165). Calculate the Heat flow in a tungston rod 1 m long with a radius of 0.1 m, where one end is at 200C and the other end is at 25C. Provide your answer in watts.

Question 1: For a Germanium semiconductor material, EĢ=1.5 eV, Fermi level is located 1.40 eV above the highest level of the valence band. If E₁ and E₂ are located 0.03 eV and 0.05 above the bottom of the conduction band, respectively. Assume room temperature (T=300 K) and KT= 0.026 eV. Answer the following: a) [10 Point] Find the density of states at energy level E₁, if the semiconductor material is Ge. b) [10] Find the density of states at energy level E2, if the semiconductor material is Si. c) [20] Find the number of states between energy levels E₁ and E2.

Question 2: The Fermi energy level for a particular material at T = 300 K is 5.50 eV. The electrons in this material follow the Fermi-Dirac distribution function. a) [10] Find the probability of an energy level at 5.80 eV being occupied by an electron. b) [10] Repeat pan (a) if the temperature is increased to T = 800 K. c) [10] Calculate the energy level where probability of finding an electron at room temperature is 75%. d) [10] Calculate the temperature at which there is 8 percent probability that a state 5eV below the Fermi level will be empty of an electron.

Question 3: a) [10] Differentiate between intrinsic and extrinsic semiconductors? Give two examples of each. b) [10] Where does the fermi energy level of an intrinsic semiconductor lies in the energy band? How does adding a p-type or n-type impurity will affect fermi energy level?

Part a: The number of transistors per IC in 1972 seems to be about 4,000 (a rough estimate by eye). Using this estimate and Moore's Law, what would you predict the number of transistors per IC to be 20 years later, in 1992? Prediction = ?

Part b. From the chart, estimate (roughly) the number of transistors per IC in 2012. Using your estimate and Moore's Law, what would you predict the number of transistors per IC to be in 2040?

Part c. Do you think that your prediction in Part b is bellevable? Why or why not?

Design an n-channel Silicon JFET with a Pinch off voltage of -20 V with following constraints: Gate width = 0.1 cm Use only Phosphorous or Born dopants Physical design parameters must be reasonable and feasible for JFET fabrication Hand Calculations: a) Must tabulate all parameters obtained, the device geometry as well as any other unknown parameters such as the channel thickness, channel length, doping densities, carriers' mobility, built-in potential, and turn off voltage (VŢ). b) Calculate substrate's resistance used. c) Calculate IDsat and VDsat for VG at 0 V, -5 V, -10 V, -15 V, must tabulate.

2. A Si crystal that is 2cm³ in size has been n-type doped uniformly at a ratio of 1 in 105. The intrinsic concentration of silicon is 1 x 10¹0 cm³ and its atomic concentration is 5 x 1022 cm³. Figure 1 shows how the drift mobility varies with dopant concentration at room temperature (300K). a) What is the donor concentration? b) What is the hole concentration? c) Using the graph in Figure 1 and your answers to a) and b), calculate the electrical resistance of the n-type doped silicon crystal. d) We now dope the silicon crystal with boron atoms instead of arsenic to create a p-type semiconductor. We again doped the crystal uniformly at a ratio of 1 in 10 What is the electrical resistance now? Compare your result to that obtained in c), giving a reason for any difference.

Under equilibrium conditions and T> OK, what is the probability of an electron state being occupied if it is located at the Fermi level?

Start with the equations for density of states as a function of energy and the Fermi function and derive the equation for the effective density of states. This question has two parts: (i) setting up the initial integral properly, and (ii) performing the steps to derive the equation for effective density of states.

Start with the Fermi function: (i) Plot it at 0 K, 100 K, 300 K, 900 K, and 2700 K (ii) Assume we are using Si with the density of states in the conduction band and valence band as we wrote down in class (reference the slides for the equation). Make 1 plot with the electron concentration on the left y axis, the hole concentration on the right y axis, and the Fermi level as the x axis. Calculate this using the full equation for electrons and holes, not the effective density of states approximation you just derived. Make another plot of the same data, but the Y axis should be log scale, not linear scale.

2. Construct and simulate the circuit shown on Figure 1 in multisim and do also the calculations by hand. a. Measure the current ID through the diode D₁ and write down its value. (6 pts.)ID= b. What is the value of the current through the resistor R₁? Write down its value. IR= C. Measure the voltage V across the diode D₁ and write down its value. VD = d. Measure the voltage VR across the resistor R₁ and write down its value. VR=