This preview shows pages 1–2. Sign up to view the full content.
Chapter 5
5.1
Chapter 5
5.1 Bandgap and photodetection
a
.
Determine the maximum value of the energy gap that a semiconductor, used as a photoconductor,
can have if it is to be sensitive to yellow light (600 nm).
b
.
A photodetector whose area is 5
10
2
cm
2
is irradiated with yellow light whose intensity is 2 mW
cm
2
. Assuming that each photon generates one electronhole pair, calculate the number of pairs
generated per second.
c
.
From the known energy gap of the semiconductor GaAs (
E
g
= 1.42 eV), calculate the primary
wavelength of photons emitted from this crystal as a result of electronhole recombination.
d
.
Is the above wavelength visible?
e
.
Will a silicon photodetector be sensitive to the radiation from a GaAs laser? Why?
5.2 Intrinsic Ge
Using the values of the density of states effective masses
m
e
* and
m
h
* in Table
5.1, calculate the intrinsic concentration in Ge. What is
n
i
if you use
N
c
and
N
v
from Table 5.1?
Calculate the intrinsic resistivity of Ge at 300 K.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
This note was uploaded on 01/20/2011 for the course EE 372 taught by Professor Johanson/kasap during the Fall '10 term at University of Saskatchewan Management Area.
 Fall '10
 Johanson/Kasap

Click to edit the document details