Basically Light of short wavelength .i.e. high energy, raises
electrons to a higher band, so the light is absorbed by the
semiconductor, while light without enough energy to raise
electrons to the next band will pass through the semiconductor.
This will be a simulation of an experiment to measure the
band gap of various samples of semiconductor's several have
quantum wells, the confinement energy of the wells can be
calculated as a simple particle in a square well.
The experiment uses a wide bandwidth quartz light and a Jyobin
von monochromatic/spectrometer, to produce monochromatic light
between 400 nm and 1200 nm. The light passing through the
semiconductor is measured with a Hamatsu photodiode, this
is a silicon photodiode so the band gap measurement is limited
by the band gap of the silicon.
The electronics are quite simple. A chopper and lock in amplifier
make sure the signal from the photodiode is not due to extraneous
light. The monochromator is controlled by a PC the PC also
reads the voltage produced by the photodiode.
I wrote a program in Visual Basic to control the PC, I still
have a set of data files from a range of about 6 samples.
I will rewrite the program to act as a simulator and include
the data files.
This will be continued when I can dig out the data files
and other information.