Article
Nanoscience & Nanotechnology
Yachen Xu, Huimin Chen, Haiyang Xu, Minyu Chen, Pengchao Zhou, Shuzhe Li, Ge Zhang, Wei Shi, Xuyong Yang, Xingwei Ding, Bin Wei
Summary: In this study, a composite structure composed of Al2O3/HfO2 with different Al2O3/HfO2 cycles prepared by atomic layer deposition (ALD) was designed to obtain high-quality ultrathin (1-12 nm) dielectric films. The film exhibited a layer growth mode and physically formed at 3 nm, with the electrically stable film thickness being 10 nm. The ALD-prepared composite strategy provides a simple and practical way to obtain high-quality dielectric films.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Yue Yang, Xiao-Ying Zhang, Chen Wang, Fang-Bin Ren, Run-Feng Zhu, Chia-Hsun Hsu, Wan-Yu Wu, Dong-Sing Wuu, Peng Gao, Yu-Jiao Ruan, Shui-Yang Lien, Wen-Zhang Zhu
Summary: Amorphous gallium oxide thin films were grown using plasma-enhanced atomic layer deposition. The films exhibited decreasing band gap energy and increased density as the temperature increased. The higher substrate temperature also resulted in increased surface roughness. Films grown at temperatures below 200 degrees C were amorphous, while the film grown at 250 degrees C showed slight crystallinity.
Article
Chemistry, Multidisciplinary
M. Isabelle Buschges, Rudolf C. Hoffmann, Anna Regoutz, Christoph Schlueter, Jorg J. Schneider
Summary: The multilayered heterostructures of In2O3, SnO2, and Al2O3 showed improved properties in thin-film transistors (TFT), with high transparency and enhanced semiconducting behavior achieved through atomic layer deposition. Incorporation of only two monolayers of Al2O3 effectively suppressed oxygen vacancies, leading to improved TFT characteristics.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Xiao-Ying Zhang, Yue Yang, Zhi-Xuan Zhang, Xin-Peng Geng, Chia-Hsun Hsu, Wan-Yu Wu, Shui-Yang Lien, Wen-Zhang Zhu
Summary: In this study, SiO2 films were deposited by remote plasma atomic layer deposition using different oxygen plasma powers. The results showed that the oxygen plasma power had a significant impact on the growth rate and surface properties of the SiO2 films. Additionally, increasing post-annealing temperature resulted in denser SiO2 films with higher refractive index and lower etch rate.
Article
Chemistry, Physical
Seo Young Jang, Hye Min Lee, Ju Young Sung, Se Eun Kim, Jae Deock Jeon, Yewon Yun, Sang Mo Moon, Joung Eun Yoo, Ji Hyeon Choi, Tae Joo Park, Sang Woon Lee
Summary: The epitaxial growth of NbN thin film was achieved for the first time using ALD with NbCl5 and NH3 as precursors. The matching lattice structure between NbN and MgO allowed for epitaxial growth with a small lattice mismatch. The Cl impurity concentration in epitaxial NbN thin films was significantly lower compared to those grown on a SiO2 substrate, potentially due to a bond length change induced by a residual strain at the NbN/MgO interface. The epitaxial growth of NbN thin films led to improved crystallinity and a 50% reduction in resistivity.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Ales Omerzu, Robert Peter, Daria Jardas, Iztok Turel, Kresimir Salamon, Matejka Podlogar, Damjan Vengust, Ivana Jelovica Badovinac, Ivna Kavre Piltaver, Mladen Petravic
Summary: The study demonstrated a significant enhancement in the photocatalytic activity of thin ZnO films grown by PE-ALD method compared to those grown by the thermal ALD method. Various structural and optical experimental techniques were employed to analyze the physical origin of this difference.
SURFACES AND INTERFACES
(2021)
Article
Chemistry, Physical
Hyeok Jae Lee, Seo Young Jang, Hye Min Lee, Ju Young Sung, Se Eun Kim, Jae Deock Jeon, Yewon Yun, Sang Woon Lee
Summary: Transition metal nitride thin films, such as TiN, are essential for memory and transistor devices as conducting electrodes. Recently, NbN thin films with a high work function (> 4.7 eV) have gained attention as replacements for TiN thin films in capacitor electrodes to reduce leakage currents. However, the conventional NbN ALD process resulted in high resistivity (> 500 mu omega center dot cm) due to residual Cl impurity (> 5%). This study proposes an alternative ALD surface reaction using H2S gas pulses to lower the Cl impurity concentration, leading to a significant decrease in resistivity (> 30%) of NbN thin films compared to the conventional NbN ALD process.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Physics, Applied
Ramin Ghiyasi, Milena Milich, John Tomko, Patrick E. Hopkins, Maarit Karppinen
Summary: Inorganic-organic superlattice (SL) thin films fabricated using ALD/MLD technique show promise for flexible thermoelectric applications, with efficient heat conduction blocking at the inorganic/organic interfaces. The ability to manipulate layer sequences precisely and coat demanding substrates like textiles makes ALD/MLD advantageous. Studies on different organic components aim to explore bonding structure importance, density difference at the interfaces, and the thickness of monomolecular organic blocking layers.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Dong-Hee Kim, Sung-Min Yoon
Summary: In this study, a three-terminal artificial synapse transistor utilizing HfO2 electrolyte-gate insulator (EGI) was proposed. The synaptic plasticity of the fabricated synapse transistor could be modulated by the movement of mobile ions in the EGI, which were dependent on the applied pulse conditions. The device emulated biological synaptic functions and demonstrated a conversion from short-term plasticity (STP) to long-term plasticity (LTP). The choice of HfO2 EGI resulted in improved long-term reliability and operational repeatability.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Materials Science, Ceramics
Seo-Hyun Moon, Soo-Hyun Bae, Young -Ha Kwon, Nak-Jin Seong, Kyu-Jeong Choi, Sung-Min Yoon
Summary: Bi-layered channel structures were introduced to enhance the carrier mobility of oxide thin film transistors. The use of IZO/IGZO bi-layered channel resulted in the highest carrier mobility when the film thickness and ALD sub-cyclic ratio were optimized. The optimum cationic compositions of the IZO and IGZO layers were also determined.
CERAMICS INTERNATIONAL
(2022)
Review
Engineering, Manufacturing
Jinxiong Li, Gaoda Chai, Xinwei Wang
Summary: Atomic layer deposition (ALD) has become an essential thin-film technology in the microelectronics industry due to its self-limited layer-by-layer growth feature and the ability to deposit conformal pinhole-free thin films with precise thickness control, especially on 3D structures. This review focuses on the surface chemistry and precursor chemistry aspects of ALD, providing a comprehensive understanding of the involved chemistry to further advance and utilize this technology. The surface chemistry of the gas-solid ALD reactions and the precursor chemistry used in ALD processes are discussed, along with emerging applications in microelectronics and future perspectives of the ALD technology.
INTERNATIONAL JOURNAL OF EXTREME MANUFACTURING
(2023)
Article
Materials Science, Multidisciplinary
Kaiwen Li, Dong Lin, Jinhua Ren, Qun Zhang
Summary: Si-doped Zn3N2 thin-film transistors (TFTs) were fabricated and investigated, showing improved performance in terms of mobility and on-off current ratio.
Article
Materials Science, Ceramics
Kwang Su Yoo, Dong-Gyu Kim, Seunghwan Lee, Won-Bum Lee, Jin-Seong Park
Summary: Atmospheric pressure spatial atomic layer deposition (AP S-ALD) derived Al2O3 films were investigated for their properties at different growth temperatures and applied in IGZO thin film transistor (TFT) fabrication. Increasing the growth temperature improved the growth per cycle, refractive index, and density of the Al2O3 films, reducing carbon impurities. The fabricated IGZO TFTs with Al2O3 layers exhibited excellent device performance and stability.
CERAMICS INTERNATIONAL
(2022)
Article
Chemistry, Multidisciplinary
Changhwan Kim, Namwook Hur, Jiho Yang, Saeyoung Oh, Jeongin Yeo, Hu Young Jeong, Bonggeun Shong, Joonki Suh
Summary: In this paper, a low-temperature ALD process is reported to achieve annealing-free growth of monoelemental vdW tellurium thin films with exceptional homogeneity, crystallinity, and layer control. The introduction of a dual-function co-reactant and the adoption of a repeating dosing technique enable the successful demonstration of electronically vdW-coupled and mixed-dimensional vertical p-n heterojunctions. The ALD-Te-based threshold switching selector with fast switching time, high selectivity, and low threshold voltage showcases the potential of this synthetic strategy for scalable production of vdW semiconducting materials for monolithic integration into arbitrary 3D device architectures.
Article
Environmental Sciences
Sunil Babu Eadi, Han Yan, P. Senthil Kumar, Yuvakkumar Rathinam, Hi-Deok Lee
Summary: In this study, the performance of IGZO-decorated ZnO films for the detection of NO2 gas was investigated by changing the IGZO deposition time. The results showed that decorating ZnO with IGZO can significantly increase the sensor response.
ENVIRONMENTAL RESEARCH
(2022)
Article
Chemistry, Inorganic & Nuclear
Jared M. Ashtree, Ivana Borilovi, Kuduva R. Vignesh, Abinash Swain, Sarah H. Hamilton, Yasmin L. Whyatt, Sophie L. Benjamin, Wasinee Phonsri, Craig M. Forsyth, Wolfgang Wernsdorfer, Alessandro Soncini, Gopalan Rajaraman, Stuart K. Langley, Keith S. Murray
Summary: The study focuses on two families of heptanuclear clusters, where two staggered dysprosium(III) triangles are linked by different M(III) d-/p-block ions, showing that varying the central metal ion M is crucial in tuning the toroidal moments on the triangular units. The use of diamagnetic M linking ions enhances the ferrotoroidic coupling, leading to specific modulation of toroidal properties.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Anirban Chandra, Mursaleem Ansari, Ines Monte-Perez, Subrata Kundu, Gopalan Rajaraman, Kallol Ray
Summary: The study explores the reactivity of mu-1,2-peroxo-bridged diiron(III) intermediates P as reactive intermediates in various biological oxidation reactions, showcasing both electrophilic and nucleophilic reactions. It also highlights the ability of mu-1,2-peroxo-bridged dimetal complexes to effect deformylation of aldehydes in biomimetic studies.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Jyoti Prasad Biswas, Mursaleem Ansari, Aniruddha Paik, Sheuli Sasmal, Sabarni Paul, Sujoy Rana, Gopalan Rajaraman, Debabrata Maiti
Summary: The study reveals that the steric and electronic effects of the non-heme ligand play a crucial role in influencing the mechanism of oxygen atom transfer reactions in olefin epoxidation, leading to the formation of different epoxide products with distinct stereochemistry. Additionally, the dominant inductive electronic effect and minor resonance effect are observed in the rate-limiting step, highlighting their contributions to electron transfer from olefin to the ferryl oxo complex.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Peter Comba, Markus Enders, Michael Grosshauser, Markus Hiller, Rudiger Klingeler, Changhyun Koo, Dennis Muller, Gopalan Rajaraman, Abinash Swain, Msia Tavhelidse, Hubert Wadepohl
Summary: The study presents single crystal data of a trinuclear complex and analyzes the ground state wavefunction accurately based on spectroscopic parameters. The experimental analysis also provides a detailed description of the Dy-III center through paramagnetic NMR spectra. The theoretical approach, supported by ab initio ligand field analysis, shows good agreement with the experimental observations, confirming the quality of the theoretical method based on a pseudo-spin Hamiltonian for the electronic ground state.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Prabhakaran Rajasekar, Abinash Swain, Gopalan Rajaraman, Ramamoorthy Boomishankar
Summary: This study reports a stable polyradical tetrahedral palladium(II) cage and reveals its stability mechanism and structure through experimental and theoretical calculations. The research shows that under specific conditions, the diradical state in the cage is more stable than the monoradical state, and there is a weak ferromagnetic exchange observed between adjacent radical centers in the DFT studies.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Inorganic & Nuclear
Ravi Kumar, Bhawana Pandey, Akta Singh, Gopalan Rajaraman
Summary: Understanding the oxidative abilities of high-valent metal-oxo species, specifically manganese-oxo species, sheds light on designing more efficient and selective catalysts. Manganese-oxo hydroperoxo species exhibit high reactivity, while manganese-oxo hydroxo and oxo species are unreactive under experimental conditions.
INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Inorganic & Nuclear
Pawan Kumar, Sourav Biswas, Abinash Swain, Joydev Acharya, Vierandra Kumar, Pankaj Kalita, Jessica Flores Gonzalez, Olivier Cador, Fabrice Pointillart, Gopalan Rajaraman, Vadapalli Chandrasekhar
Summary: A series of homometallic dinuclear lanthanide complexes with nonequivalent lanthanide metal centers have been synthesized and characterized, with complex 1 showing zero-field single-molecule magnet behavior. Detailed magnetic studies revealed the influence of nonequivalent binding of the azide co-ligand and varying coordination of the deprotonated Schiff base ligand on the magnetic properties of the metal centers.
INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Inorganic & Nuclear
Ajit Kumar Kharwar, Arpan Mondal, Arup Sarkar, Gopalan Rajaraman, Sanjit Konar
Summary: We report a new class of four dimeric Co(II) complexes with different coordination geometry of two Co(II) centers and their magnetic study. Interestingly, the two Co(II) centers show two different types of magnetic anisotropy. Ab initio calculations reveal that the six-coordinate Co(II) center possesses a consistently large negative axial zero-field splitting parameter, while the four-coordinate Co(II) center exhibits a range of D values. All the complexes display rare ferromagnetic interaction, and the strength of this interaction decreases as the ligand field on the pseudo-tetrahedral Co(II) center decreases.
INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Inorganic & Nuclear
Arup Sarkar, Reshma Jose, Harshit Ghosh, Gopalan Rajaraman
Summary: Ab initio calculations on two three-coordinate complexes show record-high magnetic anisotropy, with detailed analysis suggesting flexibility in coordination leading to barrier relaxation dominance. In silico models based on the X-ray structures of the complexes reveal larger anisotropy and robust SIM characteristics, offering design clues for low-coordinate transition-metal SIMs.
INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Physical
Asmita Sen, Vandana Gaded, Prabha Jayapal, Gopalan Rajaraman, Ruchi Anand
Summary: Guanine deaminases (GD) are essential enzymes for regulating the nucleobase pool. The study on GD from Nitrosomonas europaea reveals the mechanism of substrate fidelity, involving two amino acids (E79 and E143) and the presence of crystallographic water molecules near the active site that control reactivity. The proposed catalytic mechanism can be applied to design selective inhibitors for human GD.
JOURNAL OF PHYSICAL CHEMISTRY B
(2021)
Article
Chemistry, Inorganic & Nuclear
Thayalan Rajeshkumar, Reshma Jose, Gopalan Rajaraman
Summary: In this study, density functional theory calculations were used to estimate the exchange coupling constants within oximato bridged {Mn-6(III)} clusters, revealing a competing interaction within the cluster and closely spaced spin states. Experimental data supported the computed results, showing negligible intercluster interaction. By studying other metal ion clusters, it was suggested that introducing Cr-III could potentially alter the magnetic coupling, which could be significant for oximato bridged {Mn-6(III)} clusters.
Article
Chemistry, Inorganic & Nuclear
Lena Spillecke, Shalini Tripathi, Changhyun Koo, Mursaleem Ansari, Shefali Vaidya, Amaleswari Rasamsetty, Talal Mallah, Gopalan Rajaraman, Maheswaran Shanmugam, Rudiger Klingeler
Summary: The research investigates the influence of changing the anion in a crystal lattice on the structural distortions and magnetic behavior of the [CoS4]2+ core in a series of [Co(L1)4]X2 complexes. Experimental results demonstrate significant changes in magnetic anisotropy and exchange interactions.
Article
Chemistry, Multidisciplinary
Tanu Sharma, Mukesh Kumar Singh, Radhika Gupta, Munmun Khatua, Gopalan Rajaraman
Summary: By using theoretical tools and modeling six complexes with corannulene as a capping ligand to stabilize Dy(iii) half-sandwich complexes, a strong axiality exerted by Dy-C interactions was predicted. Among the complexes, Cp ring systems exhibit the largest barrier heights, followed by six-membered arene systems and corannulene.
Article
Chemistry, Multidisciplinary
Shalini Tripathi, Shefali Vaidya, Naushad Ahmed, Emil Andreasen Klahn, Huibo Cao, Lena Spillecke, Changhyun Koo, Sven Spachmann, Ruediger Klingeler, Gopalan Rajaraman, Jacob Overgaard, Maheswaran Shanmugam
Summary: This study reports a complex of octahedral Co(II) that exhibits an easy axis of magnetization, which has been experimentally and theoretically confirmed. By rational ligand choice, the parameters controlling the stabilization of negative D in a common octahedral geometry have been unveiled.
CELL REPORTS PHYSICAL SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Aaron J. Scott, Julia Vallejo, Arup Sarkar, Lucy Smythe, E. Regincos Marti, Gary S. Nichol, Wim T. Klooster, Simon J. Coles, Mark Murrie, Gopalan Rajaraman, Stergios Piligkos, Paul J. Lusby, Euan K. Brechin
Summary: The reaction of Ni(OTf)(2) with the bisbidentate quaterpyridine ligand L leads to the self-assembly of a tetrahedral, paramagnetic cage [(Ni4L6)-L-II](8+). By selectively exchanging the triflate, a series of host-guest complexes with encapsulated paramagnetic tetrahalometallate ions have been prepared. Magnetic susceptibility and magnetisation data suggest comparable and antiferromagnetic magnetic exchange interactions between metal ions in the host complex and the guest species.
