Conclusions

Abstract

The two facts:

• the presence of a very limited amount of impurities in a semiconductor, will substantially change the conductivity, the optical characteristics as well as other properties and

• the modern and advanced methods for growth of semiconductor quantum structures makes the fabrication of these quantum structures very controlled and accurate directly imply the importance of the area selected in this book: Impurities confined in quantum wells. The effect of shallow impurities on the emission spectra of the quantum structures has been demonstrated several times in this book, but for some applications the effect of the dopant atom itself should be avoided, e.g., due to the increased scattering resulting in a limited charge carrier mobility. In such cases, the dopant layer can be located in the barrier, outside the quantum well, but the desired charge carriers are captured into the well. In any case, the knowledge on the properties of the impurities is very important and constitutes the background for us to review the properties of shallow impurities in quantum well structures in this book. Electronic devices based on these doped quantum wells can be found in manifoldness in our daily life today and the efforts to investigate the impurity properties have been and still are extensive.