This paper focuses on the conformality of the plasma-enhanced atomic layer deposition (PE-ALD) of Al 2 O 3 using trimethylaluminum [Al(CH 3 ) 3 ; (TMA)] as a precursor and O 2 plasma as an oxidant source. The conformality was quantified by measuring the deposited film thickness as a function of depth into macroscopic test structures with aspect ratios of ~5, 10, and 22. A comparison with the thermal TMA/H 2 O process indicates that the conformality of the plasma based process is more limited due to the surface recombination of radicals during the plasma step. The conformality can slightly be improved by raising the gas pressure or the radio-frequency power. Prolonging the plasma exposure time results in further improvement of the conformality. Furthermore, there are indications that the H 2 O produced during the plasma step in the PE-ALD process for Al 2 O 3 contributes to the observed conformality through a secondary thermal ALD reaction. The conformality of Al 2 O 3 is also compared to the conformality of AlN deposited by PE-ALD from TMA and NH 3 plasma. For the same exposure, O 2 plasma results in better conformality compared to NH 3 plasma, suggesting a faster recombination of the radicals in the NH 3 plasma.

Conformality of Al2O3 and AIN Deposited by Plasma-Enhanced Atomic Layer Deposition

Highly selective CO2 gas sensor using stabilized NiO-In2O3 nanospheres coated reduced graphene oxide sensing electrodes at room temperature

Interfacial Engineering of In2O3/InN Heterostructure with Promoted Charge Transfer for Highly Efficient CO2 Reduction to Formate

Indium nitride (InN) is characterized by its high electron mobility making it a ground-breaking material for high frequency electronics. The difficulty of depositing high-quality crystalline InN cu...

In Situ Activation of an Indium(III) Triazenide Precursor for Epitaxial Growth of Indium Nitride by Atomic Layer Deposition

Deep learning for ultra-fast and high precision screening of energy materials

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 °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 (<1 at. %) and oxygen level (<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.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 °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 t...

/pdf/atomic-layer-deposition-of-inn-using-trimethylindium-and-4qa2gqi6ky.pdf

Atomic layer deposition of InN using trimethylindium and ammonia plasma

Indium nitride (InN) is an interesting material for future high-frequency electronics due to its high electron mobility. The problematic deposition of InN films currently prevents full exploration of InN-based electronics. We present studies of atomic layer deposition (ALD) of InN using In precursors with bidentate ligands forming In–N bonds: tris(N,N-dimethyl-N′,N″-diisopropylguanidinato)indium(III), tris(N,N′-diisopropylamidinato)indium(III), and tris(N,N′-diisopropylformamidinato)indium(III). These compounds form a series were the size of the substituent on the endocyclic position decreases from −NMe2 to −Me and to −H, respectively. We show that when the size of the substituent decreases, the InN films deposited have a better crystalline quality,  of better optical quality, lower roughness, and an In/N ratio closer to unity. From quantum chemical calculations, we show that the smaller substituents lead to less steric repulsion and weaker bonds between the ligand and In center. We propose that these eff...

/pdf/the-endocyclic-carbon-substituent-of-guanidinate-and-2nkknx0jvh.pdf

The Endocyclic Carbon Substituent of Guanidinate and Amidinate Precursors Controlling Atomic Layer Deposition of InN Films

Gallium nitride (GaN) is the main component of modern-day high electron mobility transistors due to its favorable electronic properties. As electronic devices become smaller with more complex surface architecture, the ability to deposit high-quality GaN films at low temperatures is required. Herein, we report a new highly volatile Ga(III) triazenide precursor and demonstrate its ability to deposit high-quality epitaxial GaN by atomic layer deposition (ALD). This new Ga(III) triazenide, the first hexacoordinated Ga-N bonded precursor used in a vapor deposition process, was easily synthesized and purified by either sublimation or recrystallisation. Thermogravimetric analysis showed single-step volatilization with an onset temperature of 155 degrees C and negligible residual mass. Three temperature intervals with self-limiting growth were observed when depositing GaN films. The GaN films grown in the second growth interval at 350 degrees C were epitaxial on 4H-SiC without an AlN seed layer and found to have a near stoichiometric Ga/N ratio with very low levels of impurities. In addition, electron microstructure analysis showed a smooth film surface and a sharp interface between the substrate and film. The band gap of these films was 3.41 eV with the Fermi level at 1.90 eV, showing that the GaN films were unintentionally n-type-doped. This new triazenide precursor enables ALD of GaN for semiconductor applications and provides a new Ga(III) precursor for future deposition processes.

https://pubs.acs.org/doi/pdf/10.1021/acs.chemmater.1c00244

Hexacoordinated Gallium(III) Triazenide Precursor for Epitaxial Gallium Nitride by Atomic Layer Deposition

Metallic thin films are key components in electronic devices and catalytic applications. Deposition of a conformal metallic thin film requires using volatile precursor molecules in a chemical vapor deposition (CVD) process. The metal centers in such molecules typically have a positive valence, meaning that reduction of the metal centers is required on the film surface. Powerful molecular reducing agents for electropositive metals are scarce and hamper the exploration of CVD of electropositive metals. The authors present a new CVD method for depositing metallic films where free electrons in a plasma discharge are utilized to reduce the metal centers of chemisorbed precursor molecules. They demonstrate this method by depositing Fe, Co, and Ni from their corresponding metallocenes using electrons from an argon plasma as a reducing agent.

/pdf/chemical-vapor-deposition-of-metallic-films-using-plasma-2czfwbt2sr.pdf

Polla Rouf

Papers

Atomic layer deposition of InN using trimethylindium and ammonia plasma

In Situ Activation of an Indium(III) Triazenide Precursor for Epitaxial Growth of Indium Nitride by Atomic Layer Deposition

The Endocyclic Carbon Substituent of Guanidinate and Amidinate Precursors Controlling Atomic Layer Deposition of InN Films

Hexacoordinated Gallium(III) Triazenide Precursor for Epitaxial Gallium Nitride by Atomic Layer Deposition

Chemical Vapor Deposition of Metallic Films Using Plasma Electrons as Reducing Agents