Article
Engineering, Electrical & Electronic
Raseong Kim, Ian A. Young
Summary: Comprehensive benchmarking analyses of Si and Ge n-and pMOSFETs at a relevant technology node reveal that strained Ge may significantly improve the efficiency of nMOS, while the improvement for relaxed Ge pMOS may be limited by tunneling leakage and the improvement by strained Ge pMOS may also be limited by increased source-to-drain tunneling. However, both Ge n-and pMOS offer additional performance benefits at higher temperatures, including increased maximum supply voltage for Ge n-and pMOS due to less increase in tunneling leakage with temperature and further improvement in efficiency for strained Ge pMOS with high temperatures. These results highlight the potential advantages of strain in Ge n-and pMOS and underscore the importance of considering operating temperature for accurate assessment of performance improvement.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Nanoscience & Nanotechnology
Gwan In Kim, Joohye Jung, Won Kyung Min, Min Seong Kim, Sujin Jung, Dong Hyun Choi, Jusung Chung, Hyun Jae Kim
Summary: This study proposes a plasma-polymerized hafnium oxide (HfOx) hybrid dielectric to achieve the synergistic advantages of outstanding flexibility in organic dielectrics and remarkable dielectric/insulating properties in inorganic dielectrics. By plasma-polymerizing high-k HfOx with polytetrafluoroethylene (PTFE), a flexible and hydrophobic fluoropolymer dielectric, the PPH-hybrid dielectric exhibits excellent flexibility and maintains a low leakage current density even after repetitive bending stress. The PPH-hybrid dielectric is also applied to amorphous indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs), demonstrating stable electrical performance and enhanced stability.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Correction
Chemistry, Multidisciplinary
Kisung Chae, Andrew C. Kummel, Kyeongjae Cho
Summary: The correction for the interface models of hafnium-zirconium oxide with a semiconductor and metal aims to enhance the performance of ferroelectric devices, as studied by Kisung Chae and colleagues in Nanoscale Adv., 2021.
NANOSCALE ADVANCES
(2021)
Article
Chemistry, Physical
Mirine Leem, Deokjoon Eom, Heesoo Lee, Kwangwuk Park, Kwangsik Jeong, Hyoungsub Kim
Summary: In this study, HZO films were grown directly on single-crystalline MoS2 flakes using ALD with H2O or O3 oxidants. The O3-based ALD process oxidizes the MoS2 surface at the atomic layer level and facilitates the conformal deposition of an HZO film without surface treatment of MoS2. Annealing the O3-based HZO film significantly improves the ferroelectric properties, but also leads to diffusion of S, Hf, Zr, and O towards the Mo layer, reducing the weak HZO bonds.
APPLIED SURFACE SCIENCE
(2023)
Article
Engineering, Electrical & Electronic
Sumit Choudhary, Daniel Schwarz, Hannes S. Funk, D. Weisshaupt, Robin Khosla, Satinder K. Sharma, Joerg Schulze
Summary: The integration of ferroelectric hafnium zirconium oxide (HZO) over the p-Ge/n-Ge(-on-)n-Si system is achieved for the first time in this study. A carrier modulation approach using depletion approximation and negative capacitance is employed to fabricate HZO and thin p-Ge channel-based FET. The optimized TaN/HZO/TaN stacks exhibit enhanced ferroelectricity and non-centrosymmetric orthorhombic phase.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Nanoscience & Nanotechnology
Zhouchangwan Yu, Balreen Saini, Yunzhi Liu, Fei Huang, Apurva Mehta, John D. Baniecki, H. -S. Philip Wong, Wilman Tsai, Paul C. McIntyre
Summary: This study systematically investigates the effects of deposition and annealing processes on Hafnia-based ferroelectric thin films. Crystallites consistent with the polar orthorhombic phase were observed in films deposited at elevated ALD temperature, and high-polarization ferroelectric switching was achieved after low-temperature rapid annealing.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
Yeonghwan Ahn, Yerin Jeon, Seokwon Lim, Jiwoong Kim, Jisu Kim, Le Thai Duy, Hyungtak Seo
Summary: This study introduces the use of plasma-enhanced atomic layer deposition (PEALD) for growing ultrathin Zr-doped hafnium oxide (HfO2-ZrO2 or HZO) nanolaminates and explores the effect of radio frequency (RF) plasma power on the electrical properties of these oxide films. The results show the notable influence of plasma power on the growth and properties of ferroelectric oxide films, with increased power leading to a decrease in film polarization. Additionally, a relationship between leakage current and the electronic structure causing film polarization is revealed.
SURFACES AND INTERFACES
(2023)
Article
Engineering, Electrical & Electronic
Meng-Chien Lee, Nien-Ju Chung, Hung-Ru Lin, Wei-Li Lee, Yun-Yan Chung, Shin-Yuan Wang, Guang-Li Luo, Chao-Hsin Chien
Summary: In this study, p-MOSFETs were successfully fabricated on SiGe substrates using TMA pre-doping and NH ₃ plasma as interfacial layer treatment. The XPS results showed that the SiGe interface treated with TMA pre-doping and NH ₃ plasma had no Ge-O bonds and was mainly composed of Si-N and Al-O bonds. With this IL treatment, the p-MOSFET demonstrated improved subthreshold swing, high $I_{{on}}$ / $I_{{off}}$ ratio, and enhanced driving current. Therefore, this proposed scheme is a simple technique to achieve a high-quality interface on a SiGe substrate.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Materials Science, Ceramics
Hsiao-Hsuan Hsu, Hsiu-Ming Liu, Sheng Lee, Chun-Hu Cheng
Summary: This study explored the effects of stress and doping on ferroelectric hafnium zirconium oxide (HfZrO) through material analysis and electrical characteristics. Stresses transferred by tantalum nitride (TaN) electrodes and Al doping can effectively modify the ferroelectric polarization characteristics of HfZrO, improving leakage current and stabilizing domain switching.
CERAMICS INTERNATIONAL
(2021)
Article
Engineering, Electrical & Electronic
Kaveh Ahadi, Ken Cadien
Summary: Gate dielectrics with enhanced capacitance density and small current leakage are critical for continuous scaling of electronic devices. Hafnium zirconate thin film grown using plasma-enhanced atomic layer deposition shows an ultra-low density of interfacial traps, highest capacitance density, and lowest leakage current.
JOURNAL OF ELECTRONIC MATERIALS
(2022)
Article
Biochemistry & Molecular Biology
Yaru Pan, Xihui Liang, Zhihao Liang, Rihui Yao, Honglong Ning, Jinyao Zhong, Nanhong Chen, Tian Qiu, Xiaoqin Wei, Junbiao Peng
Summary: Multi-component metal oxide films can achieve good performances in several aspects, such as leakage current density and capacitance density. The AMYZO(x) group has the lowest leakage current density, while the HMYZO(x) group has the highest capacitance density.
Article
Chemistry, Physical
Tahsin Ahmed Mozaffor Onik, Huzein Fahmi Hawari, Mohd Faizul Mohd Sabri, Yew Hoong Wong
Summary: The study systematically investigated the chemical, structural, and electrical properties of the Sm2O3 gate stack on Ge substrate. The results showed that Sm2O3 exhibited excellent electrical performance on Ge substrate, making it a potential gate dielectric for Ge MOS-based devices.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Joonbong Lee, Myeong Seop Song, Woo-Sung Jang, Jinho Byun, Hojin Lee, Min Hyuk Park, Jaekwang Lee, Young-Min Kim, Seung Chul Chae, Taekjib Choi
Summary: A strategy to enhance the ferroelectric properties of polycrystalline hafnium zirconium oxide (HZO) ultrathin films by modifying the oxygen pressure during device preparation is described. The formation of characteristic TiO2-x interfacial layers between the TiN electrode and HZO thin film under different oxygen treatment conditions directly impacts the distribution of the deposited HZO and facilitates the generation and stabilization of the ferroelectric orthorhombic phase HZO by promoting the uniform distribution of oxygen vacancies.
ADVANCED MATERIALS INTERFACES
(2022)
Article
Energy & Fuels
Hock Jin Quah, Zainuriah Hassan, Way Foong Lim
Summary: The study successfully fabricated high dielectric constant nitrided aluminum zirconium oxide films on silicon substrate. Different nitrogen gas flow rates affect factors such as film thickness and oxygen diffusion at the interface, impacting interface quality and film performance.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2021)
Article
Engineering, Electrical & Electronic
Hui-Hsuan Li, Yi-He Tsai, Yu-Hsien Lin, Chao-Hsin Chien
Summary: A Ge pMOSFET with Ti-doped GeOx gate stack was fabricated successfully, showing improved performance characteristics and potential for sub-nm gate dielectric on Ge substrate.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Energy & Fuels
Shankar Karki, Julia Deitz, Grace Rajan, Sina Soltanmohammad, Deewakar Poudel, Benjamin Belfore, Gandhari Bhandari, Tyler J. Grassman, Angus Rockett, Sylvain Marsillac
IEEE JOURNAL OF PHOTOVOLTAICS
(2020)
Article
Crystallography
Vinita Rogers, Julia Deitz, Ari N. Blumer, John A. Carlin, Tyler J. Grassman, Sanjay Krishna
JOURNAL OF CRYSTAL GROWTH
(2020)
Article
Energy & Fuels
Daniel L. Lepkowski, Tal Kasher, Jacob T. Boyer, Daniel J. Chmielewski, Tyler J. Grassman, Steven A. Ringel
IEEE JOURNAL OF PHOTOVOLTAICS
(2020)
Article
Physics, Applied
Zak H. Blumer, Jacob T. Boyer, Ari N. Blumer, Daniel L. Lepkowski, Tyler J. Grassman
APPLIED PHYSICS LETTERS
(2020)
Article
Chemistry, Multidisciplinary
Jacob T. Boyer, Ari N. Blumer, Zak H. Blumer, Daniel L. Lepkowski, Tyler J. Grassman
CRYSTAL GROWTH & DESIGN
(2020)
Article
Energy & Fuels
Daniel L. Lepkowski, Tal Kasher, Tyler J. Grassman, Steven A. Ringel
Summary: This study explores the use of epitaxially integrated distributed Bragg reflectors to improve the performance of monolithic GaAs0.75P0.25/Si tandem solar cells by designing an enhanced bandwidth DBR structure. Experimental data-driven analytical modeling shows that the enhancement effect of this DBR structure on current is equivalent to a 1.8x reduction in threading dislocation density, indicating its great potential in mitigating the impact of defect populations.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Energy & Fuels
Daniel J. Chmielewski, Daniel L. Lepkowski, Jacob T. Boyer, Tyler J. Grassman, Steven A. Ringel
Summary: By optimizing doping and post-growth annealing, a high-performance metamorphic Al0.2Ga0.8As0.75P0.25/GaAs0.75P0.25 heterojunction tunnel structure was developed, showing potential for high efficiency and low resistance.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Energy & Fuels
Daniel L. Lepkowski, Tyler J. Grassman, Jacob T. Boyer, Daniel J. Chmielewski, Chuqi Yi, Mattias K. Juhl, Anastasia H. Soeriyadi, Ned Western, Hamid Mehrvarz, Udo Romer, Anita Ho-Baillie, Christopher Kerestes, Daniel Derkacs, Steven G. Whipple, Alex P. Stavrides, Stephen P. Bremner, Steven A. Ringel
Summary: The study fabricated a GaAsP/Si tandem solar cell with a certified efficiency of 23.4% using MOCVD growth on an ex-situ produced Si sub cell. The key improvement in efficiency was attributed to advancements in top cell design to maximize short wavelength response, along with identification of key loss mechanisms through in-depth analysis of the tandem cell. Further efficiency gains are expected through addressing issues such as voltage dependent collection efficiency and reducing dislocation density in the top cell and implementing rear surface texture and dielectric passivation in the Si subcell.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2021)
Article
Crystallography
J. T. Boyer, A. N. Blumer, Z. H. Blumer, D. L. Lepkowski, T. J. Grassman
Summary: This study examined the impact of key parameters in metal-organic chemical vapor deposition (MOCVD) on GaP/Si heteroepitaxy, particularly focusing on Si surface preparation and GaP atomic layer epitaxy (ALE) nucleation processes. The results showed that the Si surface preparation method had little effect on the GaP film morphology and defect content, while variations in GaP ALE nucleation conditions significantly influenced threading dislocation densities in thin GaP/Si films. The study also found a substantial range of stacking fault pyramid (SFP) densities, with no apparent causal relationship between SFP density and threading dislocation density.
JOURNAL OF CRYSTAL GROWTH
(2021)
Proceedings Paper
Energy & Fuels
Daniel L. Lepkowski, Tal Kasher, Jacob T. Boyer, Zak H. Blumer, Chuqi Yi, Mattias K. Juhl, Anastasia H. Soeriyadi, Hamid Mehrvarz, Udo Roemer, Anita Ho-Baillie, Stephen P. Bremner, Steven A. Ringel, Tyler J. Grassman
Summary: This paper presents recent efforts to improve the performance of monolithically-integrated GaAsP/Si tandem solar cells by developing low-TDD GaAsP/Si virtual substrates, and demonstrates methods to enhance efficiency through optimized designs. Conversion efficiency projections suggest that achieving around 27% efficiency for the tandems is feasible with the top cell performance metrics combined with the expected improvements in the bottom cell iteration.
2021 IEEE 48TH PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC)
(2021)
Proceedings Paper
Energy & Fuels
Jacob T. Boyer, Zak H. Blumer, Daniel L. Lepkowski, Steven A. Ringel, Tyler J. Grassman
Summary: Threading dislocation density (TDD) is a crucial parameter in epitaxially integrated III-V/Si photovoltaics. The GaP/Si epitaxial bridge is a widely studied integration pathway, and recent research has shown multiple pathways to achieve low TDD, providing fundamental understanding and enabling scalable production in the field.
2021 IEEE 48TH PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC)
(2021)
Proceedings Paper
Energy & Fuels
Emily L. Warren, Annick Anctil, Silvana Ayala, Joseph J. Berry, Lyndsey McMillon-Brown, Angela N. Fioretti, Tyler J. Grassman, Mark A. Mikofski, Allison Perna, Brittany L. Smith
2020 47TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC)
(2020)
Proceedings Paper
Energy & Fuels
Vincenzo LaSalvia, William Nemeth, Jacob T. Boyer, Daniel L. Lepkowski, Emily A. Makoutz, Theresa E. Saenz, Steven A. Ringel, Tyler J. Grassman, Emily L. Warren
2020 47TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC)
(2020)
Proceedings Paper
Energy & Fuels
Daniel L. Lepkowski, Jacob T. Boyer, Chuqi Yi, Anastasia H. Soeriyadi, Zak H. Blumer, Mattias K. Juhl, Daniel Derkacs, Chris Kerestes, Alex Stavrides, Hamid Mehrvarz, Anita W. Y. Ho-Baillie, Stephen Bremner, Steven A. Ringel, Tyler J. Grassman
2020 47TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC)
(2020)
Proceedings Paper
Energy & Fuels
Jacob T. Boyer, Ari N. Blumer, Zak H. Blumer, Francisco A. Rodriguez, Daniel L. Lepkowski, Steven A. Ringel, Tyler J. Grassman
2020 47TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC)
(2020)
Article
Engineering, Electrical & Electronic
Bruno Galizia, Patrick Fiorenza, Corrado Bongiorno, Bela Pecz, Zsolt Fogarassy, Emanuela Schiliro, Filippo Giannazzo, Fabrizio Roccaforte, Raffaella Lo Nigro
Summary: This study demonstrates the growth of oriented AlN thin films on 4H-SiC substrates using PE-ALD technique, and investigates the impact of NH3 plasma pulsing on the microstructure and orientation degree of the AlN layers. The structural characterization reveals different polymorphic structures depending on the NH3 plasma pulsing time, and electrical nanoscopic characterization shows a correlation between the AlN crystalline phases and the insulating properties.
MICROELECTRONIC ENGINEERING
(2024)
Article
Engineering, Electrical & Electronic
Theo Levert, Alter Zakhtser, Julien Duval, Chloe Raguenez, Stephane Verdier, Delphine Le Cunff, Jean-Herve Tortai, Bernard Pelissier
Summary: In this study, the robustness of optical constants and optical band gap determination of three different materials is compared using a combination of spectroscopic ellipsometry and energy loss signal of X-ray photoelectron spectroscopy. The hybridization of these two techniques provides a new robust method for determining the band gap of the studied materials and other optical properties over a wide energy range.
MICROELECTRONIC ENGINEERING
(2024)