Semiconductor materials are at the core of electronics. Most electronic devices are made of
semiconductors. The operation of these components is well described by quantum physics which is
often a difficult concept for students to understand. One of the intrinsic parameters of
semiconductors is their bandgap energy ##IMG##
[http://ej.iop.org/images/0031-9120/51/2/025003/pedaa05d8ieqn001.gif] {${{E}_{text{g}}}$} . In the
case of light-emitting diodes (LEDs) ##IMG##
[http://ej.iop.org/images/0031-9120/51/2/025003/pedaa05d8ieqn002.gif] {${{E}_{text{g}}}$} fixes the
colour of the light emitted by the diodes. In this article we propose an experiment to compare
##IMG## [http://ej.iop.org/images/0031-9120/51/2/025003/pedaa05d8ieqn003.gif] {${{E}_{text{g}}}$}
of a green LED obtained by both electrical and optical measurements. The two slightly different
results can be explained by the theoretical knowledge of students…