Room temperature atomic layerlike deposition of ZnS on organic thin films: Role of substrate functional groups and precursors

Abstract

Impact of surface morphology of Si substrate on performance of Si/ZnO heterojunction devices grown by atomic layer deposition technique J. Vac. Sci. Technol. A 33, 01A114 (2015); 10.1116/1.4900719 Atomic layer deposition of ZnO on Cu-nanoclusters for methanol synthesis J. Vac. Sci. Technol. A 31, 01A144 (2013); 10.1116/1.4772460Influence of organozinc ligand design on growth and material properties of ZnS and ZnO deposited by atomic layer depositionThe room temperature atomic layerlike deposition (ALLD) of ZnS on functionalized self-assembled monolayers (SAMs) was investigated, using diethyl zinc (DEZ) and in situ generated H 2 S as reactants. Depositions on SAMs with three different terminal groups, -CH 3, -OH, and -COOH, were studied. It was found that the reaction of DEZ with the SAM terminal group is critical in determining the film growth rate. Little or no deposition is observed on -CH 3 terminated SAMs because DEZ does not react with the methyl terminal group. ZnS does deposit on both -OH and -COOH terminated SAMs, but the grow rate on -COOH terminated SAMs is $10% lower per cycle than on -OH terminated SAMs. DEZ reacts with the hydroxyl group on -OH terminated SAMs, while on -COOH terminated SAMs it reacts with both the hydroxyl and carbonyl bonds of the terminal groups. The carbonyl reaction is found to lead to the formation of ketones rather than deposition of ZnS, lowering the growth rate on -COOH terminated SAMs. SIMS spectra show that both -OH and -COOH terminated SAMs are covered by the deposited ZnS layer after five ALLD cycles. In contrast to ZnO ALLD where the composition of the film differs for the first few layers on -COOH and -OH terminated SAMs, the deposited film composition is the same for both -COOH and -OH terminated SAMs. The deposited film is found to be Zn-rich, suggesting that the reaction of H 2 S with the Zn-surface adduct may be incomplete.

Atomic Layer Deposition Nucleation on Isolated Self-Assembled Monolayer Functional Groups: A Combined DFT and Experimental Study

“…In earlier reports, Walker and co-workers performed secondary-ion mass spectrometry, XPS, and growth rate measurements of samples after the early stages of ZnO/ZnS growth on OH/COOH functionalized SAM surfaces. 47,48 Our calculations provide mechanistic insights that complement well the work of Walker et al and refine their interpretation. In particular, our calculations predict that isolated (CH 2 ) x − COOH and (CH 2 ) x −OH functional groups share a similar enthalpy of association with DEZ but that the barrier to reaction is much smaller for (CH 2 ) x −COOH.…”

Influence of low-temperature sulfidation on the structure of ZnS thin films

“…These methods include magnetron sputtering, pulsed laser deposition (PLD), metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), thermal evaporation, electrodeposition, atomic layer deposition (ALD), spray pyrolysis, spin coating, and chemical bath deposition. [13][14][15][16][17][18][19][20][21][22][23][24] Among these methods, magnetron sputter-ing has high efficiency and causes no pollution. Films prepared by magnetron sputtering exhibit good interfacial adhesion with the substrate, high compactness, and can be prepared on a large-area substrate.…”

A Novel Chemical Route to Atomic Layer Deposition of ZnS Thin Film from Diethylzinc and 1,5‐Pentanedithiol

“…Zinc sulfide (ZnS) is a wide bandgap n‐type semiconductor (3.6–3.8 eV) with transparent optical property. It has various applications such as photocatalysts, flat panel displays, and thin film photovoltaics . In order to deposit ZnS thin film by ALD, diethylzinc (DEZ) is considered as the best Zn precursor due to its high vapor pressure and applicability even at low temperatures .…”

“…The sulfur precursor for ZnS ALD is normally H 2 S gas which is very flammable and highly toxic . However, there has been no previous work for ALD of ZnS without the use of H 2 S, thus a process using a different sulfur precursor needs to be developed …”