Phosphorus is diffused into a thick slice of silicon with no
previous phosphorus in it. If the surface concentration of the
phosphorus is 1 x 10^18 atoms/cm^3, and its concentration at 1
micrometer needs to be 1 x 10^15 atoms/cm^3, after a diffusion time
of 1 hour. What is the temperature needed for the process?
Consider a Si p-n junction connected p-type and n-type
semiconductors each doped 1017 /cm3
concentration, in temperature 50K, 350K, 650K
Suppose occur energy state of conduction band quantization due
to the junction make very small.
If Si p-n junction has only three DOS(density of state) in
conduction band and valence band, Discuss band diagrams and I-V
curve.
Q1
The mobility of carriers in a lightly doped silicon sample will
decrease if :
Select one:
a. The sample is doped N-type instead of P-type
b. None of these
c. All of these
d. The temperature is increased
e. The number of dopant atoms is decreased
Q2
Electron mobility in silicon is typically lower than hole
mobility.
Select one:
True
False
Q3 If a P-type silicon sample with a hole mobility of 370
cm^2/Vs has an electric field of...
Consider an infinitely large, homogeneous n-type Si at T = 300K
doped to Nd = 2.5 x 1015cm-3 . Assume that, for t < 0, the
semiconductor is in thermal equilibrium and that, for t ≥ 0, a
uniform generation rate exists in the crystal. (a) Determine the
excess minority carrier concentration as a function of time
assuming the condition of low-level injection. (b) Assume a
generation rate of 4 x 1020 cm-3 s -1 . And let τpo =...
Consider a silicon wafer that is doped with
2.5x1017cm-3 boron (B) dopants and is at
300K. Please answer the following concerning this silicon
wafer:
a. What Group is the element boron in the periodic chart?
b. Is the boron dopant a donor or acceptor in the silicon
crystal?
c. Explain why your choice of either donor or acceptor.
d. Is the majority charge carriers electrons in the conduction
band or holes in the valence band?
e. What are the minority...
A sample of silicon is doped with donors to a concentration of
10^20 donors m−3 . Assume all the donors are ionised and that the
sample is initially at 300K. (a) What is the concentration of holes
in this sample of silicon? (b) Calculate the position of the Fermi
level in this doped sample of silicon. (c) At what temperature will
the intrinsic electron concentration become larger than the donor
electron concentration?
In an n-type semiconductor, the Fermi level lies 0.5 eV below
the conduction band. If the conduction of donor atoms is tripled,
find the new position of the Fermi level, given KT = 0.03 eV.
Doping changes the Fermi energy of a semiconductor. Consider
silicon, with a gap of 1.11 eV between the top of the valence band
and the bottom of the conduction band. At 300 K the Fermi level of
the pure material is nearly at the midpoint of the gap. Suppose
that silicon is doped with donor atoms, each of which has a state
0.13 eV below the bottom of the silicon conduction band, and
suppose further that doping raises the Fermi...
A silicon sample is doped with 4.5 × 1017
cm-3 boron atoms. Assume T= 300 K, ni = 1.5 x
1010 cm-3
What is the hole concentration and electron
concentration?