Real-time observation of nucleation and growth of Au on CdSe quantum dot templates

Abstract

Semiconductor quantum dot (QD) arrays can be useful for optical devices such as lasers, solar cells and light-emitting diodes. As the size distribution influences the band-gap, it is worthwhile to investigate QDs prepared using different solvents because each of them could influence the overall morphology differently, depending on the ligand network around individual QDs. Here, we follow the nucleation and growth of gold (Au) on CdSe QD arrays to investigate the influence of surface ligands and thereby realized interparticle distance between QDs on Au growth behaviour. We particularly emphasize on the monolayer stage as the Au decoration on individual QDs is expected at this stage. Therefore, we sputter-deposit Au on each QD array to investigate the morphological evolution in real-time using time-resolved grazing-incidence small-angle X-ray scattering (GISAXS). The growth kinetics - independent of the template - signifies that the observed template-mediated nucleation is limited only to the very first few monolayers. Delicate changes in the Au growth morphology are seen in the immediate steps following the initial replicated decoration of the QD arrays. This is followed by a subsequent clustering and finally a complete Au coverage of the QD arrays.

State of the art of ultra-thin gold layers: formation fundamentals and applications

“…In order to probe the formation process of the Au-QD interface, several efforts have been done to fundamentally study the growth processes of deposited Au on different QD arrays. 60,62,64 In an initial in situ GISAXS study N. Paul et al studied templating the growth of Au nanostructures with a CdSe quantum dot array. 60 In a later study, W. Chen et al applied in situ GISAXS to focus on the early stage of Au sputter deposition on a lead sulde (PbS) QD solid.…”

“…In recent years, both in situ and ex situ studies have been developed to focus on the growth kinetic and inuencing factors of UTGLs formation on the different substrates, including solid substrates (e.g., silicon (Si) wafers and oxides thin lms), 16,22,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] so substrates (e.g., polymer thin lms), 28,[48][49][50][51][52][53][54][55][56][57][58] and nanostructured substrates (e.g., phase-separated polymer lms, nanostructured oxides thin lms, and quantum dot arrays). [59][60][61][62][63][64] 2.1 On solid substrates Depositing Au on a at solid substrate, such as Si wafer, is regarded as the idealized case to study the UTGL growth without other inuencing factors. Therefore, many fundamental studies focused on the growth processes of UTGLs on Si wafers and other at solid substrates.…”

Probing Chemical-Composition-Induced Heterostructures and Interfaces in Lead Halide Perovskites

“…With the advance in synthetic strategies, different heterostructured materials are regularly produced. These heterostructured materials includes metal–metal (Au/Ag, Ag/Cu 3 P, and Ag/Cu) metal–semiconductor (Au/PbS, Au/CdSe, and Au/CdS), and semiconductor–semiconductor (CdS/ZnSe, CdSe/CdS, and CdS/CdTe) materials as shown in Figure (a–d). Furthermore, the semiconductor–semiconductor heterostructure can be classified as type-I (high band gap shell on top of a low band gap core or vice versa) and type-II (band position are offset such that in the valence band maxima (VBM)/conduction band minima (CBM) of one semiconductor lies between the band gap region of the other semiconductor) heterostructures as shown in Figure (e,f).…”