Doped and Codoped Silicon Nanocrystals: the Role of Surfaces and Interfaces

TL;DR

This review discusses recent advances in understanding how doping and surface chemistry influence the electronic and optical properties of silicon nanocrystals, highlighting theoretical and experimental insights into dopant behavior and interface effects.

Contribution

It provides a comprehensive summary of recent theoretical and experimental studies on doping, codoping, and surface effects in silicon nanocrystals, emphasizing ab-initio calculations and size-dependent phenomena.

Findings

Doping behavior in Si nanocrystals differs from bulk silicon.

Surface and interface chemistry significantly influence dopant localization.

Size and passivation affect doping efficiency and electronic properties.

Abstract

Si nanocrystals have been extensively studied because of their novel properties and their potential applications in electronic, optoelectronic, photovoltaic, thermoelectric and biological devices. These new properties are achieved through the combination of the quantum confinement of carriers and the strong influence of surface chemistry. As in the case of bulk Si the tuning of the electronic, optical and transport properties is related to the possibility of doping, in a controlled way, the nanocrystals. This is a big challenge since several studies have revealed that doping in Si nanocrystals differs from the one of the bulk. Theory and experiments have underlined that doping and codoping are influenced by a large number of parameters such as size, shape, passivation and chemical environment of the silicon nanocrystals. However, the connection between these parameters and dopant localization as well as the occurrence of self-purification effects are still not clear. In this review we summarize the latest progress in this fascinating research field considering free-standing and matrix-embedded Si nanocrystals both from the theoretical and experimental point of view, with special attention given to the results obtained by ab-initio calculations and to size-, surface- and interface-induced effects.