ABSTRACT
Looking at these shortcomings, it is evident that one must rummage around for alternative methods to increase injection eciency in LEDs. Providentially, doping of impurities is not the solitary way to change injection eciency. e composition of the semiconductor material itself can be altered to fashion the same eect. By changing the material composition
and hence energy gap as a function of distance, one can tailor the potential prole and thereby monitor the injection eciency. Structures composed of semiconductors having dierent energy gaps are known as heterostructures (Lundstrom 1997, Zhao 1997), and are realized by bandgap engineering. It must be emphasized that extreme prudence is necessary in choosing material combinations from the viewpoint of lattice matching, otherwise defects will be produced at the interfaces between semiconductors leading to the abhorred nonradiative recombination. e recompense oered will then be annulled to a great extent by loss of carriers through the nonradiative route.
