The DR in Quantum Dot HDSLs

Abstract

In this chapter, the DR from III–V, II–VI, IV–VI, HgTe/CdTe and strained layer quantum dot heavily doped superlattices (QDHDSLs) with graded interfaces has been studied in Sects. 15.2.1 to 15.2.5. From Sects. 15.2.6 to 15.2.10, the DR from III–V, II–VI, IV–VI, HgTe/CdTe and strained layer quantum dot heavily doped effective mass superlattices respectively has been presented. The DRs for QDHDSLs of HD materials exhibit the fact that the total energy is quantized since the corresponding wave vector space is totally quantized. The DOS functions for all the materials in this case are series of non-uniformly distributed Dirac’s Delta functions at specified quantized points in the respective energy axis. The spacing between the consecutive Delta functions are functions of energy band constants and quantization of the wave vector space of a particular material. It may be noted that the HD QDHDSLs lead to the levels, somewhat like atomic energy levels, which produce very large changes. This follows from the inherent nature of the quantum confinement of the carrier gas dealt with here. In QDHDSLs, there remain no free carrier states in between any two allowed sets of levels unlike that found for QWs and NWs super-lattices where the quantum confinements are 1D and 2D, respectively. Consequently, the crossing of the Fermi level by the size-quantized levels in HD QDHDSLs would have much greater impact on the redistribution of the carriers among the allowed levels, as compared to that found for QWs and super-lattices respectively. The quantum signature of HD QDHDSLs for the DR is rather prominent as compared to the same from QWs and NWs super-lattices. It is the band structure which changes in a fundamental way and consequently all the physical properties of all the electronic materials changes radically leading to new physical concepts. The Sect. 15.4 contains single open research problems, which form the integral part of this chapter.

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