Experiment 4 - The Photovoltaic Effect
The photovoltaic effect occurs when light shines onto the n-layer.
Since this layer is thin, light can penetrate into the np-junction,
where it encounters electron-hole pairs...
If the light hits an electron-hole pair,
the electron and the hole are separated...
by the positive space charge the electron
is pulled into the n-layer, and
by the negative space charge the hole
is pulled into the p-layer.
Illustration photovoltaic effect.
This causes a voltage of about 0.5 volts between the contacts.
To obtain, for example, a solar cell with a nominal voltage
of 3 Volt, you connect internally six solar cells in series...
Illustration setup solar cell with 3 volts nominal voltage.
Back to some circuits...