Ligand-Free, Colloidal, and Plasmonic Silicon Nanocrystals Heavily Doped with Boron

Abstract

Colloidal heavily doped silicon nanocrystals (Si NCs) exhibiting tunable localized surface plasmon resonance (LSPR) are of great interest in cost-effective, solution-processed optoelectronic devices given the abundance and nontoxicity of Si. In this work we show that tunable plasmonic properties and colloidal stability without the use of ligands can be simultaneously obtained for Si NCs heavily doped with boron (B). The heavily B-doped Si NC colloids are found to be stable in air for months, opening up the possibility of device processing in ambient atmosphere. The optical absorption of heavily B-doped Si NCs reveals that the heavy B doping not only changes the concentration of free carriers that are confined in Si NCs but also modifies the band structure of Si NCs. After heavy B doping both indirect and direct electronic transition energies remarkably decrease in Si NCs because the heavy B doping induced movement of the conduction band toward the band gap could be more significant than that of the Fermi level into the valence band. The LSPR of heavily B-doped Si NCs originates from free holes above the Fermi level, which are largely from the B-induced impurity band.

Plasmonic doped semiconductor nanocrystals: Properties, fabrication, applications and perspectives

“…[11] Depending on the size and doping level of the nanostructure, LSPRs from the visible through the terahertz can be reached. [11] Strategies to intentionally add dopant atoms to the crystal of a semiconductor nanostructure have seen rapid progress and various doped semiconductor NCs were synthesized, [8] including phosphorous and boron-doped silicon NCs, [14][15][16] aluminum, germanium, or indium doped zinc oxide, [17] and indium doped tin oxide (ITO) NCs. [9] All these NCs have intense resonances in the mid to near IR due to plasmonic absorption.…”

Si/SiO2 Core/Shell Luminescent Silicon Nanocrystals and Porous Silicon Powders With High Quantum Yield, Long Lifetime, and Good Stability

“…Luminescent Si nanocrystals (SiNCs) are intensively studied for their potential applications in diverse fields, such as optoelectronics, sensing, and medicine [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Some particularly important characteristics of such SiNCs include absolute quantum yield (AQY), stability, luminescence lifetime, surface chemistry, and synthesis route.…”

Structures, Oxidation, and Charge Transport of Phosphorus‐Doped Germanium Nanocrystals

“…For elemental semiconductor NCs such as Si NCs gas‐phase doping has been found to be effective . It has been shown that the structural, electronic, and optical properties of Si NCs can be tuned by doping …”

“…[20][21][22] It has been shown that the structural, electronic, and optical properties of Si NCs can be tuned by doping. [23][24][25][26][27][28] As another type of important elemental semiconductor NCs, Ge NCs hold a unique position because of a series of advantageous materials properties, including strong optical absorption and high mobilities of electronic carriers. [ 29 ] Although Ge NCs can now be controllably synthesized, [30][31][32] the doping of Ge NCs has been rarely explored.…”