ESE 521 The Physics of Solid State Energy Devices

ESE 521 The Physics of Solid State Energy Devices

Homework #4

1. A p-n abrupt junction with NA=1017/cm3 and ND=5x1015/cm3 has τp=0.1 µs and τn=0.01 µs with kT=0.026 eV, A=10-4 cm2, ni=1010/cm3, µn=801 cm2/Vs and µp=438 cm2/Vs.

  • Calculate the reverse saturation current due to holes.
  • Calculate the reverse saturation current due to electrons.
  • Calculate the total reverse saturation current.
  • If VA= Vbi/2, calculate the injected minority carrier currents at the edges of the depletion region. What are the injected minority carrier concentrations at 0 and 1 µm into the bulk regions?
  • If VA= -Vbi/2, calculate the injected (depleted) minority carrier concentrations at the edges of the bulk regions? Calculate the minority carrier currents at the edges of the depletion regions.
  • At what value of VA and where in the diode will the assumption of "low-level injection" first be violated? Use the criterion of the minority carrier reaching 10% of the majority carrier concentration as the violation.

2. A silicon step junction diode with a cross-sectional area A=10-4 cm2 has a doping of NA=1017/cm3 and ND=1015/cm3. Let µn=801 cm2/Vs and τn=0.1 µs on the p-side; and let µp=477 cm2/Vs and τp=1 µs on the n-side.

  • Calculate the current through the diode at room temperature if
    • VA= -50 V
    • VA= -0.1 V, and
    • VA= 0.2 V
  • Assuming that the mobilities and lifetimes do not vary significantly with temperatures. repeat part (a) for T=500 K.
  • Summarize in your own words what has been exhibited by this problem.

3. A p+-n silicon step junction is doped NA=1018/cm3and ND=1016/cm3 where Ecr=4x105 V/cm with ni=1010/cm3 (kT =0.026 eV). Calculate:

  • VBR;
  • the depletion width at V
  • If ND=1017/cm3 repeat part (a)

Want latest solution of this assignment

Want to order fresh copy of the Sample Template Answers? online or do you need the old solutions for Sample Template, contact our customer support or talk to us to get the answers of it.