Quantum dot energy relaxation mediated by plasmon emission in doped covalent semiconductor heterostructures

Abstract

The interaction between interface plasmons within a doped substrate and quantum dot electrons or holes has been theoretically studied in double heterostructures based on covalent semiconductors. The interface plasmon modes, the corresponding dispersion relationship, and the intraband carrier relaxation rate in quantum dots are reported. We find the critical points in the interface plasmon density of states for multilayered structures results in enhanced quantum dot intraband carrier relaxation when compared to that for a single heterostructure. A detailed discussion is made of the relaxation rate and the spectral position dependencies on the quantum dot layer thickness as well as on the dopant concentration. The material system considered was a p-Si/ SiO 2 / air heterostructure with Ge quantum dots embedded in an SiO 2 layer. This structure is typical of those used in technical applications.

Electronic Properties of Surface Vacancies in CdS Nanocrystals

“…Особливо це виявляється в люмінесцентних характеристиках нанокристалів. У більшості випадків спектр фотолюмінесценції таких нанокристалів визначається лише міжзонними переходами, широко описаними в літературі [9][10][11]. Тим не менш, у спектрах люмінесценції нанокристалів халькогенідів кадмію може спостерігатися люмінесценція з участю рівнів, що асоціюються з дефектами [12].…”

Time-resolved pump-probe spectroscopy of intraband absorption by a semiconductor nanorod

“…Many types of relaxation mechanisms were proposed to explain the experimental data evidencing that the intraband relaxation rate inside semiconductor NCs vary over a wide range from 10 8 to 10 13 s -1 . These include: (i) the two-photonassisted relaxation on optical and acoustic phonons; 21 (ii) the relaxation due to the coherent interaction of optical phonons with the electronic subsystem of the NCs; 22 (iii) the relaxation facilitated by the finiteness of the lifetime of optical phonons; 23 (iv) the relaxation mediated by the emission of plasmon and plasmon-phonon modes [24][25][26][27][28][29][30][31] residing in the regions located tens of nanometers away from the NC; (v) the relaxation due to the interaction with the NC's surface defects; [32][33][34] (vi) the multiphoton-induced relaxation, 35 (vii) Auger processes; 36 and (viii) the nonradiative energy transfer processes. 37,38 In this work, we develop a theory of pump-probe optical spectroscopy based on the pump-pulse-induced transient intraband absorption of the probe's pulse inside an anisotropic semiconductor nanorod-a quantum NC in the form of a straight circular cylinder or a rectangular parallelepiped.…”

Engineering Optical Activity of Semiconductor Nanocrystals via Ion Doping

“…The detection of enantiomeric forms of chiral molecules is only possible through their interaction with other chiral objects [6][7][8]. Semiconductor nanocrystals, which are often intrinsically chiral because of the unavoidable surface and bulk defects, are objects of particular promise owing to their distinctive photoluminescence properties [9][10][11][12][13][14][15][16]. It has been recently demonstrated that CdSe/ZnS quantum dots and quantum rods can acquire chirality from screw dislocations naturally developing during their growth [17][18][19][20].…”