The doping is normally applied to a thin layer on the top of the cell, producing a pn-junction with a particular bandgap energy, E g.
12.
The bandgap energy of GaInAs can be determined from the peak in the photoluminescence spectrum, provided that the total impurity and defect concentration is less than cm " 3.
13.
The bandgap energy depends on temperature and increases as the temperature decreases, as can be seen in Fig . 3 for both n-type and p-type samples.
14.
Changing the geometry of the surface of the quantum dot also changes the bandgap energy, owing again to the small size of the dot, and the effects of quantum confinement.
15.
In general, the exciton eigen energies consist of a series of bound states that emerge energetically well below the fundamental bandgap energy and a continuum of unbound states that appear for energies above the bandgap.
16.
For instance, in semiconductors, most of the light emitted is at the frequency corresponding to the bandgap energy, i . e . from the bottom of the conduction band to the top of the valence band.
