Question

Notify Me Bookmark

Suppose that NA(x) = No exp(-x/L) in a region of silicon extending from x = 0 to x = 8 µm, where No is a constant. Assume that p(x) = NA(x). Assuming that jp must be zero in thermal equilibrium, show that a built-in electric field must exist and find its value for L = 1 µm and No = 10^18/cm3.

Suppose that NA(x) = No exp(-x/L) in a region of silicon extending from x = 0 to x = 8 µm, where No is a constant. Assume that p(x) = NA(x). Assuming that jp must be zero in thermal equilibrium, show that a built-in electric field must exist and find its value for L = 1 µm and No = 10^18/cm3.

Image text
Suppose that NA(x) = No exp(-x/L) in a region of silicon extending from x = 0 to x = 8 µm, where No is a constant. Assume that p(x) = NA(x). Assuming that jp must be zero in thermal equilibrium, show that a built-in electric field must exist and find its value for L = 1 µm and No = 10^18/cm3.

Detailed Answer

2 0

Please enter your email here. You will get email when this question is answered by our tutor.

Answer
Doubtrix Logo

This Problem has been solved!

You'll get a detailed, step-by-step and expert verified solution.

Join Doubtrix with 7-days free trial

  • Icon Correct & Verified Answers
  • Icon No AI-Generated Answers
  • Icon Video Solution for Difficult Questions
  • Icon Work With Experts to Reach at Correct Answers
Login Sign Up
  • Student Reviews:
  • (2)
  • Correct answers (2)
  • Complete solution (2)
  • Step-by-step solution (2)
  • Fully explained (2)

Similar/Related Questions

10a) (15 Points) In the following circuit, an NMOS transistor is used to switch the current to the LED. Assume the following parameters: Microcontroller: vO = 4.6 V iOH < −5 mA and vOL = 0.4 V, iOL < 8 mA LED: vf = 2.0 V, PLED−max = 200 mW Desired LED current 100 mA Transistor: vT = 1.0 V, RDS(ON) = 0.5 Ω, iD−max = 500 mA a. When the output of the microcontroller is low, what is the operating region of the transistor? b. When the output of the microcontroller is high, what is the operating region of the transistor? c. With the microcontroller output high, and the transistor in the ohmic region, what value of R results in an on-state LED current of 100 mA? d. What standard value of resistor (Table is on page 33 of the text) comes closest to the desired LED current? 10b) Suppose we rearrange the NMOS circuit in problem 10 as shown. Using the same parameters as in the previous problem, answer the following: a. When the output of the microcontroller is low, what is the operating region of the transistor? b. Suppose that when the output of the microcontroller is high, there is 100 mA current through the LED with the same resistor as found in problem 10a. What is the source voltage relative to ground? What is the gate-source voltage? c. Do you expect this arrangement to work for controlling the LED? Explain. 10c) (15 Points) In this problem, the NMOS transistor in problem 10b has been replaced with a PMOS transistor as shown. Assume all the parameters are the same, noting that the gate must be the threshold voltage below the source to get out of cutoff. a. When the output of the microcontroller is high, what is the operating region of the transistor? b. When the output is low, what is the operating region of the transistor? c. Does this arrangement to work for controlling the LED? Explain.10a) (15 Points) In the following circuit, an NMOS transistor is used to switch the current to the LED. Assume the following parameters: Microcontroller: vO = 4.6 V iOH < −5 mA and vOL = 0.4 V, iOL < 8 mA LED: vf = 2.0 V, PLED−max = 200 mW Desired LED current 100 mA Transistor: vT = 1.0 V, RDS(ON) = 0.5 Ω, iD−max = 500 mA a. When the output of the microcontroller is low, what is the operating region of the transistor? b. When the output of the microcontroller is high, what is the operating region of the transistor? c. With the microcontroller output high, and the transistor in the ohmic region, what value of R results in an on-state LED current of 100 mA? d. What standard value of resistor (Table is on page 33 of the text) comes closest to the desired LED current? 10b) Suppose we rearrange the NMOS circuit in problem 10 as shown. Using the same parameters as in the previous problem, answer the following: a. When the output of the microcontroller is low, what is the operating region of the transistor? b. Suppose that when the output of the microcontroller is high, there is 100 mA current through the LED with the same resistor as found in problem 10a. What is the source voltage relative to ground? What is the gate-source voltage? c. Do you expect this arrangement to work for controlling the LED? Explain. 10c) (15 Points) In this problem, the NMOS transistor in problem 10b has been replaced with a PMOS transistor as shown. Assume all the parameters are the same, noting that the gate must be the threshold voltage below the source to get out of cutoff. a. When the output of the microcontroller is high, what is the operating region of the transistor? b. When the output is low, what is the operating region of the transistor? c. Does this arrangement to work for controlling the LED? Explain.10a) (15 Points) In the following circuit, an NMOS transistor is used to switch the current to the LED. Assume the following parameters: Microcontroller: vO = 4.6 V iOH < −5 mA and vOL = 0.4 V, iOL < 8 mA LED: vf = 2.0 V, PLED−max = 200 mW Desired LED current 100 mA Transistor: vT = 1.0 V, RDS(ON) = 0.5 Ω, iD−max = 500 mA a. When the output of the microcontroller is low, what is the operating region of the transistor? b. When the output of the microcontroller is high, what is the operating region of the transistor? c. With the microcontroller output high, and the transistor in the ohmic region, what value of R results in an on-state LED current of 100 mA? d. What standard value of resistor (Table is on page 33 of the text) comes closest to the desired LED current? 10b) Suppose we rearrange the NMOS circuit in problem 10 as shown. Using the same parameters as in the previous problem, answer the following: a. When the output of the microcontroller is low, what is the operating region of the transistor? b. Suppose that when the output of the microcontroller is high, there is 100 mA current through the LED with the same resistor as found in problem 10a. What is the source voltage relative to ground? What is the gate-source voltage? c. Do you expect this arrangement to work for controlling the LED? Explain. 10c) (15 Points) In this problem, the NMOS transistor in problem 10b has been replaced with a PMOS transistor as shown. Assume all the parameters are the same, noting that the gate must be the threshold voltage below the source to get out of cutoff. a. When the output of the microcontroller is high, what is the operating region of the transistor? b. When the output is low, what is the operating region of the transistor? c. Does this arrangement to work for controlling the LED? Explain.
Solution
0 0

A 5-µm-long block of p-type silicon has an acceptor doping profile given by NA(x) = 10^14 + 10^18 exp(-10^4x), where x is measured in cm. Use Eq. (2.17) to demonstrate that the material must have a nonzero internal electric field E. What is the value of E at x = 0 and x = 5 µm? (Hint: In thermal equilibrium, the total electron and total hole currents must each be zero.)
Solution
0 0

Consider MOSFET-based current source circuits shown below. Assume that the n-type MOSFET transistors follow the long-channel model with μnCox = 100 μA/V2 and Vth,n = 0.5 V. All the transistors have a fixed channel length L = 0.25 μm. The bias voltage VB1 is at 0.8 V. Assume that all transistors have no back-bias effect. (1) (2) (a) For a basic current source in Fig. (1), size the NMOS transistor M1's width ( = W1) so that it conducts a current of 1 mA when it operates in saturation region. You may assume λn = 0. (b) What is the minimum value of Vout for this circuit that keeps M1 in saturation region? (c) For a cascode current source in Fig. (2), assume that the transistor M2 has the same width with M1 you determined from part (a). Determine the value of VB2 that yields the lowest minimum VOUT keeping both M1 and M2 in saturation regions. (d) Now, let's assume that the transistors M1 and M2 have a finite output resistance with λn = 0.1 V−1. Compute the value of the output resistance (Rout) of this cascode current source when M1 and M2 are in the saturation region. (Hint: Calculate the output impedance in a small signal equivalent circuit.)
Solution
0 0