Atomic layer deposition of InN using trimethylindium and ammonia plasma

Indium nitride (InN) is a low bandgap, high electron mobility semiconductor material of interest to optoelectronics and telecommunication. Such applications require the deposition of uniform crystalline InN thin films on large area substrates, with deposition temperatures compatible with this temperature-sensitive material. As conventional chemical vapor deposition (CVD) struggles with the low temperature tolerated by the InN crystal, the authors hypothesize that a time-resolved, surface-controlled CVD route could offer a way forward for InN thin film deposition. In this work, the authors report atomic layer deposition of crystalline, wurtzite InN thin films using trimethylindium and ammonia plasma on Si(100). They found a narrow atomic layer deposition window of 240-260 degrees C with a deposition rate of 0.36 A/cycle and that the flow of ammonia into the plasma is an important parameter for the crystalline quality of the film. X-ray diffraction measurements further confirmed the polycrystalline nature of InN thin films. X-ray photoelectron spectroscopy measurements show nearly stoichiometric InN with low carbon level (amp;lt;1 at. %) and oxygen level (amp;lt;5 at. %) in the film bulk. The low carbon level is attributed to a favorable surface chemistry enabled by the NH3 plasma. The film bulk oxygen content is attributed to oxidation upon exposure to air via grain boundary diffusion and possibly by formation of oxygen containing species in the plasma discharge. Published by the AVS.Funding Agencies|Swedish Foundation for Strategic Research through the project "Time-resolved low temperature CVD for III-nitrides" [SSF-RMA 15-0018]; Knut and Alice Wallenberg foundation through the project "Bridging the THz gap" [KAW 2013.0049]; VR [VR 2016-05362]; Carl Trygger Foundation</p

On the dynamics in chemical vapor deposition of InN

Epitaxial nanometer-thin indium nitride (InN) films are considered promising active layers in various device applications but remain challenging to deposit. We compare the morphological evolution and characterizations of InN films with various growth conditions in chemical vapor deposition (CVD) by both a plasma atomic layer deposition (ALD) approach and a conventional metalorganic CVD approach. Our results show that a time-resolved precursor supply is highly beneficial for deposition of smooth and continuous InN nanometer-thin films. The time for purging the reactor between the precursor pulses and low deposition temperature are key factors to achieve homogeneous InN. The gas exchange dynamics of the reactor is further studied using computational fluid dynamics. According to our study, 320 &amp; DEG;C is found to be the upper temperature where the dynamics of the deposition chemistry can be controlled to involve only surface reactions with surface species. The results highlight the promising role of the ALD technique in realizing electronic devices based on nanometer-thin InN layers.Funding Agencies|Swedish Foundation for Strategic Research through the project "Time-resolved low temperature CVD for III-nitrides" [SSF-RMA 15-0018]; Knut and Alice Wallenberg Foundation through the project "Bridging the THz gap" [KAW 2013.0049]; Carl Trygger Foundation; Swedish Research CouncilSwedish Research CouncilEuropean Commission [2018-05973]</p

Surface Ligand Removal in Atomic Layer Deposition of GaN Using Triethylgallium

Gallium nitride (GaN) is one of the most important semiconductor materials in modern electronics. While GaN films are routinely deposited by chemical vapor deposition at around 1000 °C, low-temperature routes for GaN deposition need to be better understood. Herein, we present an atomic layer deposition (ALD) process for GaN-based on triethyl gallium (TEG) and ammonia plasma and show that the process can be improved by adding a reactive pulse between the TEG and ammonia plasma, making it an ABC-type pulsed process. We show that the material quality of the deposited GaN is not affected by the B-pulse, but that the film growth per ALD cycle increase when a B-pulse is added. We suggest that this can be explained by removal of ethyl ligands from the surface by the B-pulse, enabling a more efficient nitridation by the ammonia plasma. We show that the B-pulsing can be used to enable GaN deposition with a thermal ammonia pulse, albeit of X-ray amorphous films

Area-Selective Atomic Layer Deposition of Noble Metals: Polymerized Fluorocarbon Layers as Effective Growth Inhibitors

Selective deposition is a powerful self-aligned precision materials processing strategy which can hugely benefit next-generation nanoelectronics, catalysis, and energy conversion/storage fields. Atomic layer deposition (ALD) is showing a significant promise in enabling area-selective deposition using various growth blocking layers including self-assembled monolayers (SAMs) and various polymers. However, these blocking layers are not compatible with energetic co-reactants like ozone and plasma radicals, showing relatively fast degradation and losing their growth inhibition character. In this work, we demonstrate that polymerized fluorocarbon surfaces function as effective growth inhibitors for ALD-grown Pt and Pd films. Besides effectively inhibiting film growth with considerable nucleation delays for, Pt experiments revealed that polymerized CFx layers are also ozone-compatible. To the best of our knowledge, this is the first demonstration of an AS-ALD process using ozone as co-reactant for noble metals. In our manuscript, we detail our observations of (Pt,Pd) film nucleation evolution and self-aligned deposition experiments on patterned samples. We have performed in-depth chemical and surface characterizations along the nucleation studies and self-aligned patterning experiments.</p

Surface ligand removal in atomic layer deposition of GaN using triethylgallium

Gallium nitride (GaN) is one of the most important semiconductor materials in modern electronics. While GaN films are routinely deposited by chemical vapor deposition at around 1000 degrees C, low-temperature routes for GaN deposition need to be better understood. Herein, we present an atomic layer deposition (ALD) process for GaN-based on triethyl gallium (TEG) and ammonia plasma and show that the process can be improved by adding a reactive pulse, a "B-pulse" between the TEG and ammonia plasma, making it an ABC-type pulsed process. We show that the material quality of the deposited GaN is not affected by the B-pulse, but that the film growth per ALD cycle increases when a B-pulse is added. We suggest that this can be explained by the removal of ethyl ligands from the surface by the B-pulse, enabling a more efficient nitridation by the ammonia plasma. We show that the B-pulsing can be used to enable GaN deposition with a thermal ammonia pulse, albeit of x-ray amorphous films.Funding Agencies|Swedish Foundation for Strategic Research through the project "Time-resolved low-temperature CVD for III-nitrides" [SSF-RMA 15-0018]; Knut and Alice Wallenberg Foundation through the project "Bridging the THz gap" [KAW 2013.0049]; Carl Trygger Foundation</p

On the dynamics in chemical vapor deposition of InN

Epitaxial, nanometer-thin indium nitride (InN) films are considered as promising active layers in various device applications but remains challenging to deposit. We compare the morphological evolution and characterizations of InN films with various growth conditions in chemical vapor deposition (CVD), by both a plasma atomic layer deposition (ALD) approach and a conventional metalorganic CVD approach. Our results, and previous literature, show that a time-resolved precursor supply is highly beneficial for deposition of smooth and continuous InN nanometer-thin films. We show that the time for purging the reactor between the precursor pulses and low deposition temperature are key factors to achieve homogeneous InN. Our study suggests that 320 °C is the upper temperature where the dynamics of the deposition chemistry can be controlled to involve only surface reactions with surface species. The results highlight the promising role of the ALD technique in realizing electronic devices based on nanometer-thin InN layers

Resolving impurities in atomic layer deposited aluminum nitride through low cost, high efficiency precursor design

Synthesis, characterization, and use of an amidoalane precursor for the deposition of high-quality and low-impurity aluminum nitride films by atomic layer deposition. This study highlights the importance of smart precursor design in order to deposit high-quality thin films at low cost and high efficiency

Resolving Impurities in Atomic Layer Deposited Aluminum Nitride through Low Cost, High Efficiency Precursor Design

A heteroleptic amidoalane precursor is presented as a more suitably designed candidate to replace trimethylaluminum (TMA) for atomic layer deposition of aluminum nitride (AlN). The lack of C-Al bonds and the strongly reducing hydride ligands in [AlH2(NMe2)](3) (1) were specifically chosen to limit impurities in target aluminum nitride (AlN) films. Compound 1 is made in a high yield, scalable synthesis involving lithium aluminum hydride and dimethylammonium chloride. It has a vapor pressure of 1 Torr at 40 degrees C and evaporates with negligible residual mass in thermogravimetric experiments. Ammonia (NH3) plasma and 1 in an atomic layer deposition (ALD) process produced crystalline AlN films above 200 degrees C with an Al:N ratio of 1.04. Carbon and oxygen impurities in resultant AlN films were reduced to &amp;lt;1% and &amp;lt;2%, respectively. By using a precursor with a rational and advantageous design, we can improve the material quality of AlN films compared to those deposited using the industrial standard trimethylaluminum and could reduce material cost by up to 2 orders of magnitude.Funding Agencies|Swedish foundation for Strategic Research through the project "Time-resolved low temperature CVD for III-nitrides" [SSF-RMA 15-0018]; Vinnova VINNMER Marie Curie incoming mobility program (Vinnova)Vinnova [2015-03714]</p

Atomic Layer Deposition of AlN on Graphene

Graphene is a material with great promise for several applications within electronics. However, using graphene in any such application requires its integration in a stack of thin layers of materials. The ideal structure of graphene has a fully saturated surface without any binding sites for chemisorption of growth species, making film growth on graphene highly challenging. Herein, an attempt to deposit very thin layers of AlN using an atomic layer deposition approach is reported. It is demonstrated using X-ray photoelectron spectroscopy that Al-N are formed in the films deposited on graphene and shown by scanning electron microscopy and atomic force microscopy that the films have an island morphology. These results may be considered promising toward the development of a growth protocol for AlN on graphene and possibly also for 2D AlN fabrication.Funding Agencies|Bulgarian National Science FundNational Science Fund of Bulgaria [DN 18/6]; Swedish Foundation for Strategic Research through the project "Time-resolved low-temperature CVD for III-nitrides" [SSF-RMA 15-0018]; Knut and Alice Wallenberg Foundation through the project "Bridging the THz gap" [KAW 2013.0049]; Carl Trygger Foundation at the Linkoping University</p