bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Plasma and Wet Processes on Si-Rich Anti-Reflective Coating to Address Selective Trilayer Rework for Sub-20nm Technology Nodes
Authors: Pollet Olivier , Sommer Romain , Lachal Laurent , Barnola Sebastien , De Buttet Come , Richard Claire , Jenny Cecile
Published: October 2013

When performing trilayer rework in advanced technology nodes, removing only the top photoresist selectively to the underlying Si-containing anti-reflective coating raises advantages in terms of cost, cycle time and defectivity. However Si-BARC materials exhibit a high sensitivity to usual lithography rework processes, in that their physical or optical properties, thickness or chemical composition are readily affected. These modifications can induce a shift in lithography process window, making the process impossible in the most extreme cases. Therefore, the preferred trilayer rework process so far remains the removal of the entire stack. This article reports the extensive study of Si-BARC modifications versus rework process, including both plasmas and chemical treatments. The most innocuous processes were then tested regarding their capability to remove 193nm photoresists on top of the SOC + Si-BARC stack.
Wet-Chemical Etching of InGaAs for Advanced CMOS Processing
Authors: Dorp Dennis H. van , Arnauts S. , Cuypers Daniel , Rip Jens , Holsteyns Frank , De Gendt Stefan
Published: October 2013

In this work the etching kinetics of (100) InGaAs is studied at the nanoscale with ICP-MS for HCl/H2O2 mixtures. It is shown that the etch rate is controlled by both the concentration of the acid and the oxidizing agent. Surprisingly, an increase in etch rate is observed when the HCl concentration is decreased from 1M to 0.01 M. This can be ascribed to a surface termination effect. AFM shows that the surface roughens after exposure to 1M HCl/0.01M H2O2, possibly due to buildup of amorphous As. Ultimately, the surface needs to be cleaned of oxide. HCl can be used for this purpose. Contact angle measurements indicate that a minimum of 1M HCl solution is needed for oxide removal.
Self-Assembly of Alkanethiols to Protect GaAs(100)
Authors: Mancheno-Posso Pablo , Muscat Anthony J.
Published: October 2013

A comparative study of the chemical passivation of GaAs(100) using alkanethiols (R-SH, R=CnH2n+1) with different carbon chain lengths (n=3-18) was performed using spectroscopic ellipsometry, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and water contact angle. The time required to reoxidize the surface when exposed to the ambient scaled with the length of the chain. A threshold of about 12 C atoms was necessary for minimal protection. 1-octadecanethiol (OT-18C) containing 18 C atoms prevented reoxidation for 3 min. The OT-18C self-assembled into a monolayer containing closely packed molecules at a tilt angle from the surface normal of about 28°. The crystalline structure presented a physical barrier to oxygen diffusion with a thickness of 2.2 nm. Alkanethiols could offer ease of deposition and removal with protective properties to enable the use of III-V materials in high volume manufacturing.
Study of InP Surfaces after Wet Chemical Treatments
Authors: Cuypers Daniel , Dorp Dennis H. van , Tallarida Massimo , Brizzi Simone , Rodriguez Leonard , Conard Thierry , Arnauts Sophia , Schmeisser Dieter , Adelmann Christoph , De Gendt Stefan
Published: October 2013

In this work synchrotron radiation photoemission spectroscopy (SRPES) is used to study InP surfaces after different wet chemical treatments. All results are compared to a typical fingerprint of surface components present on an as received InP sample. It is shown that acidified (HCl and H2SO4) treatments efficiently remove the native phosphate, although components like P0, In0 and P(2±Δ)+ remain present. In alkaline solution (NH4OH) oxide remains present at the surface. As an alternative treatment, the immersion into (NH4)2S was studied. This passivation treatment results in fewer surface components which suggests that a higher quality surface is obtained.
Surface Processing for Area Selective Mist Deposition of Nanocrystalline Quantum Dot Films
Authors: Chao Ju-Hung , Kshirsagar Aditya , Ruzyllo Jerzy
Published: October 2013

This study explores surface engineering for the purpose of selective deposition of cadmium selenide (CdSe) nanocrystalline quantum dot (NQD) thin films using the process of mist deposition. Surfaces of silicon and/or glass substrates were made uniformly hydrophobic by exposure to trichloro (1H,1H,2H,2H-perfluorooctyl) silane (FOTS) anhydrous hexane solution. Subsequent localized UV exposure increased surface energy making it locally hydrophilic, and thus, allowing area selective deposition of NQD film. Electric field involved in the mist deposition process was shown to reverse process selectivity through the electrowetting effect. The role of IR rapid optical surface treatment (ROST) in controlling surface energy of FOTS material was explored. Findings of this study will allow area selective deposition of the variety of NQD precursors in the form of colloidal solution.
Trace Metal Analysis of Cleanroom Dry Wipers by Inductively Coupled Plasma – Mass Spectrometry
Authors: Liu Shi , Liu Bin
Published: October 2013

Cleanroom dry wipers were tested for trace metals by ultrapure water extraction, acid extraction, and high temperature ashing followed by Inductively Coupled Plasma – Mass Spectrometry analysis. All wipers showed high level titanium at 0.15 - 0.18 wt. %. Trace metals extracted by ultrapure water were limited even with sonication and results from dilute nitric acid extraction were hundreds of times higher, possibly due to improved solubility of metal/metal oxide/salt. Metal results from high temperature ashing process were the highest as ashing released all metals, attached to and embedded in the wiper, for acid digestion. The effects of acid composition, acid concentration, extraction time, and extraction temperature on metal extraction were also investigated. Results indicated one hour extraction at 80oC extracted more metal than twenty-four hour extraction at room temperature and hydrofluoric acid - hydrogen peroxide mixture was more effective than nitric acid in most cases.
(Invited) Origins for Fermi Level Control in Metal/High-k/Si Stacks with Inserted Dielectric Layers
Authors: Eizenberg Moshe , Kornblum Lior
Published: October 2013

Ultrathin dielectric capping layers are a prominent route for tuning band offsets and threshold voltages of advanced devices. Recent results obtained for several materials systems are presented and discussed. Ta2O5 is shown to be able to suppress the known dipole at Al2O3-SiO2 interfaces. In a different system, the diffusion of Al inside an Al2O3-capped HfO2-based device is studied in detail. The effect of the high temperature diffusion of Al to the HfO2-SiO2 interface is demonstrated, and presence of Al at that interface is correlated with the expected band offsets. La2O3 deposited in a similar way is known to have an opposite electrostatic effect. We show that La has a fundamentally different diffusion behavior under high temperatures, and that unlike Al it does not stop at the HfO2-SiO2 interface, but rather penetrates deep into the SiO2.
(Invited) Vertical III-V Nanowire-Channel on Si
Authors: Tomioka Katsuhiro , Fukui Takashi
Published: October 2013

We report on the recent achievement of III-V nanowire applications for a vertical FET and steep subthreshold-slope transistors on Si. III-V nanowires (NWs) were heterogeneously integrated on Si by selective-area metal-organic vapor-phase epitaxy with precise positioning on Si(111) surfaces. Nanometerscale growth enabled the integration of III-V NWs on Si regardless of apparent lattice mismatches. A non-planar vertical transistor architecture, which is a vertical surrounding-gate structure, was demonstrated on Si substrate. This demonstration should have broad applications for use in high-electron mobility transistors and tunnel FETs with functionality that is not possible with conventional Si-CMOS technologies.
(Invited) Nanoscale Heterogeneous Reactions and Interfaces in Ge/Si and for III-V on Si Integrated Devices
Authors: Dayeh Shadi , Tang Wei , Nguyen Binh-Minh , Dai Xing , Liu Yang , Hwang Yoontae , Liu X. -H. , Chen Renjie
Published: October 2013

In the pursuit of realizing sub-10 nm transistor channel lengths in homogenous and heterostructured materials, nanoscale defects and hetero-interfaces can significantly impact the formation of alloyed metal contacts conventionally used in CMOS devices. We utilize in-situ transmission electron microscopy to unveil new observations on the detailed formation of such alloys and interfaces at an atomic scale by capturing single nucleation events during the reaction of Ni with Si, Ge and Ge/Si core/shell nanowires and assess their resultant transistor performance. We then utilized the NiSi reaction to develop a novel heterogeneous integration process for III-V semiconductors on planar and patterned Ni electrodes in a fab-compatible process. We demonstrate the operation of the first InGaAs FinFETs on Si.
Effect of Precursor Entrance Sequence during Atomic Layer Deposition on the Al2O3/Ge Interface by X-ray Photoelectron Spectroscopy
Authors: Xiang Jinjuan , Wang Guilei , Li Tingting , Cui Hushan , Wang Xiaolei , Xu Gaobo , Li Junfeng , Wang Wenwu , Zhao Chao
Published: October 2013

The effect of precursor entrance sequence during atomic layer deposition (ALD) on the chemical and electronic characteristics of Al2O3/Ge interface is investigated by X-ray photoelectron spectroscopy (XPS) and capacitance-voltage (C-V) measurement. The trimethyla-luminium (TMA) or H2O precursor is first introduced into the chamber to grow Al2O3 dielectric on cleaned Ge. An abrupt Al2O3/Ge interface without interlayer is obtained for both cases. The valence band offset (VBO) at the Al2O3/Ge interface becomes smaller when the TMA precursor is first introduced. It is due to the lower CNL of gap states at Al2O3/Ge interface which is induced by the TMA treatment of Ge surface. Comparable gap state density at Al2O3/Ge interface are observed by C-V, indicating that the density states of gap states is not affected by the precursor pulse sequence. As a result, the precursor pulse sequence affects the CNL of gap states but not their density.
(Invited) Optimization of WAl2O3Cu(-Te) Material Stack for High-Performance Conductive-Bridging Memory Cells
Authors: Goux Ludovic , Kim Woosik , Opsomer Karl , Belmonte Attilio , Kar G. S. , De Stefano F. , Afanas'ev Valery V. , Celano U. , Houssa Michel , Devulder W. , Detavernier C. , Muller R. , Vandervorst W. , Jurczak Malgorzata
Published: October 2013

In this paper, we optimize the thermal stability of WAl2O3Cu and WAl2O3Cu-Te conductive-bridging cells for integration of 1-Transistor/1-Resistor (1T1R) memory elements. Thermal stability up to the back-end-of-line (BEOL) processing temperature of 400°C is ensured by Cu-Te composition tuning and carbon alloying developments, while Cu in-diffusion processes during BEOL processing is limited through the engineering of thin Ti-, Ta-, and TiW-based metallic liners inserted at the Al2O3Cu(-Te) interface. The integrated 1T1R cells are demonstrated to operate in the nanosecond range using moderate voltages. Write endurance of >106 cycles is achieved using 10ns-short pulses while high voltage-disturb robustness is observed at lower voltages, resulting in excellent voltage-time characteristics of the cells. Finally, images of device filaments programmed in low- and high-resistance states are successfully obtained by means of conductive atomic-force-microscopy
(Invited) The Role of Electrochemical Interfaces in ReRAM Memory Cells
Authors: Valov Ilia , Tappertzhofen Stefan , Linn Eike , Waser Rainer
Published: October 2013

The influence of non-equilibrium states and the ambient on the state properties and the switching kinetics of redox based resistive switching memories (ReRAM) is discussed. It has been demonstrated that the underlying electrochemical processes can be studied with an atomic resolution using the atomic switch concept. We address a crucial issue on the necessity of counter charge/reaction in oxide based devices and shown that moisture often supplies this counter charge.
Chemical Vapor Deposition of MoS2 Films
Authors: Mun Jihun , Kim Dongbin , Yun Juyoung , Shin Yonghyeon , Kang Sangwoo , Kim Taesung
Published: October 2013

The MoS2 films were deposited on the titanium nitride (TiN) substrate using chemical vapor deposition (CVD) method. The molybdenum hexacarbonyl (Mo(CO)6) and hydrogen sulfide (H2S) as a precursor and reaction gas, respectively. Preliminary analysis of Mo(CO)6 which decomposed about 200 degree Celsius under low pressure condition was carried out using Fourier transform infrared spectroscopy (FT-IR). The MoS2 films deposited under the various substrate temperature, chamber pressure, and flow rate were analyzed using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The result of Raman spectroscopy shows the bulk MoS2 Raman shift for samples deposited on the specific conditions.
Refined Characterization Up to Millimeter Waves of Ferroelectric KTN Thin Film for Efficient Integrated Tunable Devices
Authors: Houzet Gregory , Lacrevaz Thierry , Bermond Cedric , Le Febvrier Arnaud , Députier Stephanie , Guilloux-Viry Maryline , Queffelec Patrick , Fléchet Bernard
Published: October 2013

A KTa0.65Nb0.35O3 thin film has been deposited by Pulsed Laser Deposition on MgO substrate. By means of specific metallization patterns, such as CPW transmission lines and interdigitated capacitors, a broad-band characterization of devices is performed from 40 MHz up to 67 GHz with the superposition of static E-field to polarize the ferroelectric KTN film. Next, the complex permittivity of the 400nm KTN thin film is deduced from these HF measurements using a refined extraction procedure. Results show a distributed relaxation on all the frequency range, ruled by a Cole-Davidson model. Results on tunability of the capacitance devices are promising and reach a value of 64% under a static E-field of 400 kV/cm.
(Invited) Vanadium Dioxide for Selector Applications
Authors: Radu Iuliana P. , Govoreanu Bogdan , Martens Koen , Toeller Michael , Peter Antony P. , Ikram M. R. , Zhang Le Qi , Hody Hubert , Kim Woosik , Favia Paola , Conard Thierry , Chou Hsing Yi , Put Brecht , Afanasiev Valery V. , Stesmans Andre , Heyns Marc , De Gendt Stefan , Jurczak Malgorzata
Published: October 2013

We are assessing how VO2 and the metal to insulator transition can be used for selector applications. We report on two types of devices: diodes with VO2/TiO2 and devices with just VO2 between metal electrodes. We also examine materials issues arising from fabricating these devices. Furthermore, we analyze performance of the VO2 selector when combined with a HfOx RRAM memory cell.
Electrodeposition and Characterization of ZnO Rods Films
Authors: Santos Vanessa Nascimento dos , Machado Sergio Antonio Spinola
Published: October 2013

We discuss the electrosynthesis and characterization of vertically aligned ZnO nanorods films on different substrates using the electrodeposition technique. SEM and EDX analysis showed CQAu and ITO substrates were the most efficient in obtaining ZnO rods. Optical microscopy images showed a film thickness of 2.22 µm. The characterization by X-ray diffraction showed characteristic peaks of ZnO in wurtzite crystalline form. DRS afforded the energy bandgap of 3.43 eV. By Mott-Schottky analysis was possible to determine the flat-band potential of -0.18 V and the carriers density of 2.02 x 1020 cm-3. Scan linear sweep voltammagram upon illumination and in dark showed a pronounced photocurrent of 91 μA cm-2 at 1.2 V and corroborated with Mott-Schottky analysis in determinations of the flat-band potential. In the study of photocurrent was obtained a value of 12 μAcm-2 at 0.5 V. Thus, the ZnO rods synthesized consisting in a promising material for applications in photovoltaic devices.
(Invited) Extremely Short Channel Si-MOSFETs Prepared on SOI Substrates Using Anisotropic Wet Etching
Authors: Migita Shinji , Morita Yukinori , Masahara Meishoku , Ota Hiroyuki
Published: October 2013

Electrical properties of extremely short channel Si-MOSFETs are examined. Nanometer-scale channels are fabricated by the V-shape groove formation on SOI substrate using anisotropic wet etching technique. The channel length, defined as the width of the Vgroove bottom, is as short as 3 nm. Source, channel, and drain regions are uniformly highly doped by the same dopant species. Excellent transistor characteristics with threshold voltages that are optimal for low-power operation are obtained for both n-FETs and p-FETs when the thicknesses of both the channel and gate dielectric film thickness are reduced to 1 nm. Contributions of quantum effects in the nanometer-scale channel are discussed.
(Invited) High-Performance Field-Effect-Transistors on Monolayer-WSe2
Authors: Liu Wei , Cao W. , Kang Jiahao , Banerjee Kaustav
Published: October 2013

Monolayer Tungsten Diselenide (WSe2) exhibits tremendous advantages as a channel material for next-generation field-effect-transistors (FETs). This paper reviews the relevant physics and properties of WSe2 and highlights the excellent scalability of monolayer WSe2 for ultra-short channel (sub-5 nm) FETs. The crucial role of metal-WSe2 contacts in determining the performance of monolayer WSe2 FETs is also emphasized using experiments guided by ab-initio density functional theory (DFT). With a suitably chosen contact, a back-gated monolayer WSe2 FET on Al2O3 substrate is shown to exhibit both high mobility and high ON-current.
A Two-Step Electrical Degradation Behavior in α-InGaZnO Thin-Film Transistor
Authors: Pan Tung-Ming , Chen Fa-Hsyang , Chen Ching-Hung , Lin Ching-Chang , Cheng Chieh , Ko Fu-Hsiang , Lin Wu-Hsiung , Chen Po-Hsueh , Her Jim-Long , Matsud Yasuhiro H.
Published: October 2013

In this study, we explored the threshold voltage instability behavior in amorphous indium-gallium-zinc oxide (α-IGZO) thin-film transistor (TFT). A tow-step electrical degradation behavior of α-IGZO TFT was found under gate-bias stress. A usual small positive shift followed by a special negative shift of threshold voltage is characterized in the α-IGZO TFT. We suggest that the positive shift of the threshold voltage is because of charge trapping in the gate dielectric and/or at the channel/dielectric interface, while the negative shift of threshold voltage may be attributed to electric field induced extra electron carriers from H2O molecules in the back channel protective layer.
Measurement of Complex Conductance in the PHz Frequency Range with Subnanometric Spatial Resolution: Application to the Grain Boundary of Monoclinic Hafnia
Authors: Guedj Cyril
Published: October 2013

The spatial evolution of local complex conductivity across a grain boundary of hafnia has been measured using energy filtered high-resolution transmission electron microscopy and valence electron energy loss spectroscopy (HRTEM-VEELS). A local increase in the real part of the conductivity and the effective electron density inside the grain boundary is clearly evidenced. This methodology could be advantageously used to study the leakage pathways and the regions susceptible to early dielectric breakdown in the most advanced dielectric stacks, to further optimize the technological developments of this highly demanding industry.
(Invited) Electron Band Alignment at Ge/Oxide and AIII-BV/Oxide Interfaces from Internal Photoemission Experiments
Authors: Afanas'ev Valery V. , Chou Hsing- Yi , Houssa Michel , Stesmans Andre
Published: October 2013

Application of internal photoemission spectroscopy for determination of energy barriers and band offsets at interfaces of semiconductor crystals with deposited oxide insulators is overviewed. Systematic analysis of the results allows one to reveal several general trends in the evolution of the interface band alignment including the common anion rule and the band offset transitivity rule, which enables evaluation of the band offsets on the basis of the semiconductor and insulator bandgap width values.
Investigation on Oxygen Diffusion in a High-k Metal-Gate Stack for Advanced CMOS Technology by XPS
Authors: Kechichian Ardem , Barboux Philippe , Gros-Jean Mickael
Published: October 2013

X-ray photoelectron spectroscopy was used to study the post deposition annealing of a TiN/HfO2/SiO2/Si stack with a HfO2 thickness varying between 2nm and 5nm. Although the annealing was performed in 5N nitrogen, the growth of a SiO2 layer was observed but only in the presence of the TiN layer. It seems that the TiN layer catalyzes the oxidation with oxide anions crossing the HfO2 layer which acts as a solid electrolyte. Oxidation occurs in two steps, a fast one associated to oxide ions coming from the native TiO2 layer on top of the TiN gate-electrode and a slower one associated to the reduction of residual oxygen in the chamber. The system acts similarly to a solid oxide fuel cell between gaseous oxygen and silicon separated by HfO2. The annealing step leaves residual dipoles at the TiN/HfO2 and SiO2/Si interfaces which are the origins of energy shifts between the XPS peaks.
Effects of Non-Complexing Additives on Electrodeposited Cu(InGa)Se2 (CIGSe) Thin Film
Authors: Lucas Francisco Willian de Souza , Mascaro Lucia Helena
Published: October 2013

Thin film of Cu(InGa)Se2 (CIGSe) is a very promising semiconductor material as absorber layers for solar cell and photoelectrochemical hydrogen production application. The electrodeposition may be one effective alternative to vacuum based techniques of CIGSe fabrication. The use of additives in electrodeposition can to cause interesting effect on the growth and structure of the films. Thus, this work evaluated main effects of non-complexing additives (Glycerol and Triton 100-X) on electrodeposited CIGSe thin films. It was observed changes in the microstructure in the grain size of the deposits and this promotes differences in the carriers density, flat-band potential and others properties of the films.
Improved Characteristics for Metal-nGaSb Ohmic Contact by Using Indium Gallium Zinc Oxide (IGZO)
Authors: Shin Jeong-Hun , Jung Hyun-Wook , Park Jin-Hong
Published: October 2013

We introduce an excellent Ohmic contact technique in n-type GaSb by using a thin (~ 5 nm thick) Indium Gallium Zinc Oxide (IGZO), achieving a high on-current density of 6.804 A/cm3 and a low on/off-current ratio of 1.64 and also resolving Fermi level pinning problem near the valence band edge. A thin IGZO on n-type GaSb annealed at 500°C before metal deposition contributes to Ohmic contact formation because of two main causes; (1) InSb narrows the energy bandgap and (2) free Sb as traps induces tunneling current.
Electrochemical and Hydrothermal Synthesis of Epitaxial Arrays of Doped ZnO Nanowire Emitters for Light Emitting Diodes With Tunable Emission From Near-UV to Blue
Authors: Pauporté Thierry , Lupan Oleg , Viana Bruno
Published: October 2013

The bandgap control of doped-ZnO nanowires is important for tunable light emitting diodes (LEDs). Ultraviolet (UV), violet, blue and near-white LED structures based on Cu- or Ag-doped ZnO /p-GaN and Cd-alloyed ZnO (Zn1-xCdxO) nanorods or nanowires (NWs)/p-GaN heterojunction have been fabricated by epitaxial electrodeposition and hydrothermal growth at low temperatures. A single UV electroluminescence (EL) peak centered at around 397 nm was observed at room temperature for pure ZnO nanowires/p-GaN. The emission was shifted to 405-450 nm by using heterojunction between Cu or Ag-doped ZnO and Zn1-xCdxO-nanorods grown on p-GaN substrate. Moreover, the shift could be tuned by changing the dopant concentration. The electroluminescence emission threshold voltage was low at about 5.0 V and EL intensity increased with the applied forward voltage bias. In the case of Cu-doped ZnO prepared by hydrothermal growth, a near-white electroluminescence was achieved. The presented experimental results demonstrate the tunable emission from transition metal-doping in ZnO-based nanoLEDs.
Effect of Current Density on Pore Formation in n-InP in KOH
Authors: Quill Nathan , Lynch Robert P. , O'Dwyer Colm , Buckley D. Noel
Published: October 2013

InP samples which were galvanostatically anodised in 5 mol dm-3 KOH exhibited crystallographic pore etching at current densities ranging from 1 mA cm-2 to 20 mA cm-2. Surprisingly, the total charge at growth termination (~1.8 C cm-2) and the corresponding layer thickness (~3.0 µm) were independent of current density in experiments at continuous constant current. Surface pit density was proportional to current density, indicating that the average current per pit was 1.7 pA, independent of current density. The influence of mass transport on the termination of porous layer growth was demonstrated in an experiment at low current density where the current was interrupted a number of times before layer growth ended. At low current densities, pores had sharp tips, triangular cross-sections and large pore widths. At higher current densities, both the pore tips and the pore cross-sections became more rounded while the pore width decreased. These variations are explained in terms of the effect that different rates of hole supply (at different current densities) can have on the rate of indium vacancy formation on the three {111}A faces that make up the pore tip.
Functionalization of Thermally Carbonized Porous Silicon Optical Multilayer Structures for Sensing Applications
Authors: Salonen Jarno , Mäkilä Ermei , Urata Tomoko , Torres-Costa Vicente , Jalkanen Tero
Published: October 2013

Some general points regarding the fabrication of thermally carbonized and hydrocarbonized porous silicon-based optical filters are discussed. The differences between the two carbonization treatments are pointed out, and methods for further functionalization are presented. Finally, the effects of the aforementioned surface functionalization methods are evaluated, and usefulness of the resulting chemically modified optical structures in biosensing applications is demonstrated.
Waveguide-Mode Sensors with a Waveguide Layer Nanostructured by Dynamic Oblique Deposition
Authors: Suzuki Motofumi , Takagaki Munehito , Kuriyama Shohei , Nakajima Kaoru , Kimura Kenji
Published: October 2013

We applied oblique deposition technique to fabricate a porous waveguide layer in waveguide-mode sensors. SiO2 layer as the waveguide layer deposited at 67° shows nanocolumnar structure. Effective refractive index of the waveguide layer depends on the analyte as 1.28 for air, 1.41 for H2O and 1.42 for C2H5OH so that the large shift of resonance angle has been successfully achieved. The effective refractive index of the waveguide layer is understood by Bruggeman’s effective medium model. In order to improve sensor sensitivity, more porous layer is desirable.
Sensitivity Enhancement of Metal-Oxide-Semiconductor Tunneling Photodiode with Trapped Electrons in Ultra-Thin SiO2 Layer
Authors: Chen Tzu-Yu , Hwu Jenn-Gwo
Published: October 2013

The enhancement in the photo sensitivity of Si-based MOS tunneling photodiode with ultra-thin SiO2 layer is demonstrated by simple bias treatment in this work. After applying negative constant voltage stress (negative CVS) onto the device, a few electrons would be trapped in the ultra-thin SiO2 layer. The trapped electrons would result in a large decrease in the dark current at positive bias. Therefore, the photo sensitivity of the device could be enhanced. Besides, different stressing voltages of the negative CVS applied onto the device are utilized to achieve different amounts of trapped electrons. Thus, different photo sensitivities of the device could be obtained by these different treatments. The appropriate amount of trapped electrons resulting in the maximum value of the sensitivity also would be expected.
CMOS Logic Devices and Gas Sensors Realized by Epitaxially Transferred 2-D III-V Nanoribbons on Insulator
Authors: Shin Sungho , Nah Junghyo
Published: October 2013

We demonstrate the performance of low dimensional electronic devices realized by epitaxially transferred ultrathin III-V nanoribons. First, the performance of proof-of-concept CMOS logic gate devices is demonstrated using InAs n-channel material and InAs/InGaSb/InAs heterostructure nanoribbons as p-channel material. Next, the size scaling effects in gas sensors was then investigated using InAs NRs as a platform to realize Pd-functionalized hydrogen sensors. Lastly, parts-per-billion level NO2 gas detection was also been demonstrated without any surface functionalization.
Threshold Tuning of III-V Nanowire Transistors via Metal Clusters Decoration
Authors: Han Ning , Wang Fengyun , Ho Johnny C , Yip S. P. , Lin H. , Xiu F. , Fang M. , Yang Z. X. , Hung T. F. , Hong J. C.
Published: October 2013

Recently, III-V semiconductor nanowires are widely explored as field effect transistor (FET) materials for the next generation high speed electronics. Further tuning the working mode of the nanowire FET is essential in the large scale device design and fabrication, which is still a significant challenging in the current moment. In this study, decoration of metal nanoparticles with different work functions can effectively tune the threshold (VTH) of III-V nanowire FETs. Specifically, high work function metals such as Au and Pt can shift VTH to the positive side while low work function metals such as Al can tune VTH to the negative side, for the typical InAs, InP and InGaAs NWFETs, by depleting electrons from and donating electrons to the III-V nanowire channels. Furthermore, the fabrication of inverters using the depletion and enhancement mode InAs NWFETs show the great potency of the metal decoration method in low-power and high performance electronic devices.
Electroluminescence of n-Ge/i-Ge/p-Si Hetero Junction PIN LEDs
Authors: Kim Taek Sung , Kil Yeon-Ho , Yang Hyeon Deok , Yang Jong-Han , Kim Joung Hee , Jeong Joo Yong , Kang Sukill , Jeong Tae Soo , Choi Chel-Jong , Shim Kyu-Hwan
Published: October 2013

A pin LED was fabricated from the n-Ge/i-Ge/p-Si hetero junction structure grown by using RTCVD. The structural properties of the n-Ge/i-Ge/p-Si hetero junction structure were investigated using high-resolution X-ray diffraction (HRXRD). Specifically, the recent advances in the dry etching of n-Ge/i-Ge/p-Si hetero junction structure have been used to define pin LED n-Ge/i-Ge layer mesas. I-V characteristics of the pin LED indicate a reasonable reverse saturation current of 140 μA at -1V. The roll-off in electroluminescence spectra after wavelength of 1700 nm is expected due to the decreased emission of n-Ge/i-Ge/p-Si pin LED at room temperature.
Memristive Devices for Computing: Mechanisms, Applications and Challenges
Authors: Yang J. Joshua , Choi Byung Joon , Zhang Min-Xian , Torrezan Antonio C. , Strachan John Paul , Williams R. Stanley
Published: October 2013

Memristive devices are two terminal electrical resistance switches that can retain a state of internal resistance based on the history of applied voltage and current. These devices can be used for computing by both storing and processing information. The switching mechanisms, applications and challenges are reviewed in this paper.
(Invited) Low Temperature Direct Bonding 3D Stacking Technologies for High Density Device Integration
Authors: Di Cioccio Lea , Radu Ionut , Gaudin Gweltaz , Lacave Thomas , Baudin Floriane , Sadaka Mariam , Signamarcheix Thomas
Published: October 2013

3D integration aims at providing highly integrated systems by vertically stacking and connecting various materials, technologies, and functional components together. We will review the different approaches, using direct bonding, developed to address 3D devices manufacturing challenges.
(Invited) The Effect of Carbon Doping on Structural and Magnetic Properties of Mn5Ge3/Ge Heterosctructures
Authors: Spiesser Aurelie , Dau Minh-Tuan , Michez Lisa A , Petit Matthieu , Le Thanh Vinh
Published: October 2013

The Mn5Ge3 compound, thanks to its room-temperature ferromagnetism, metallic character and ability to epitaxially grow on germanium, has emerged as a potential candidate for spin injection into group-IV semiconductors. We investigate the effect of carbon doping in epitaxial Mn5Ge3 films and show that incorporation of carbon into interstitial sites of Mn5Ge3 can allow not only to enhance the magnetic properties but also increase the thermal stability of Mn5Ge3 up to a temperature as high as 850 °C. These results open perspectives to realize spintronic devices based on Mn5Ge3Cx/Ge heterostructures that are compatible with the Si-based complementary metal-oxide-semiconductor (CMOS) technology.
Low-Frequency-Noise-Based Oxide Trap Profiling in Replacement High-k/Metal-Gate pMOSFETs
Authors: Simoen Eddy Roger , Lee Jae-Woo , Veloso Anabela , Paraschiv Vasile , Horiguchi Naoto , Claeys Cor
Published: October 2013

Low-frequency noise is studied in planar high-k-metal/gate (HKMG) last pMOSFETs in order to study the impact of a post-HfO2 deposition SF6-plasma or heat treatment on the oxide trap density and profile. It is shown that the gate oxide quality is improved by lowering the active border trap density for both approaches. At the same time, a detailed analysis of the frequency exponent of the flicker noise spectra reveals that in the case of the SF6-plasma, the reduction of the active border trap density occurs more efficiently deeper in the high-k layer, while the opposite holds for the annealed devices, i.e., a lower trap density is found closer to the interfacial SiO2 layer.
(Invited) Unit Steps of an ALD Half-Cycle
Authors: Blomberg Tom
Published: October 2013

ALD is based on exposing the substrate sequentially to selflimiting surface reactions with two or more reactants. The elemental step of the ALD deposition method is called the halfcycle, i.e. the pulse and purge step of one precursor. While in the open literature, the ALD deposition has vigorously been studied from the surface chemistry point of view, the fundamental unit steps from an engineering point of view are much less studied subjects. In this paper, the unit steps that an ALD reactor has to perform in order to approach the ideal ALD half-cycle, namely a square wave partial pressure pulse followed by perfect purging of the reactor are discussed.
(Invited) Vapor Phase Surface Functionalization Using Atomic Layer Deposition (ALD) and Self Assembled Molecules (SAMs)
Authors: Sundaram Ganesh M. , Lecordier Laurent , Bhatia R.
Published: October 2013

The growing adoption of Atomic Layer Deposition (ALD), as a means of producing highly uniform and conformal thin films, has paved the way for its use in an array of extremely important emerging technologies. Within this class of self-limiting deposition techniques, Self-Assembled Monolayer (SAMs) are gaining visibility as a means of functionalizing surfaces. The ability to use both SAMs and ALD together has enabled some unique applications, and presents an opportunity to study the intersection of these two thin film methods. In this work, an overview of SAMs and ALD deposition work will be presented, along with results of in-situ analysis of the growth of ALD films on the SAMs surfaces. Additionally, surface functionalization results using the hybrid ALD/SAMs combination will be explored along with prospective applications.
VO2 Films Prepared by Atomic Layer Deposition and RF Magnetron Sputtering
Authors: Tangirala Madhavi , Zhang Kai , Nminibapiel David , Pallem Venkateswara , Dussarrat Christian , Cao Wei , Adam Thomas N , Johnson Corbet S , Elsayed-Ali Hani , Baumgart Helmut
Published: October 2013

Among the many vanadium suboxides and different stoichiometries, VO2 has received considerable attention due to its remarkable metal-insulator transition (MIT) behavior, which causes a significant reversible change in its electrical and optical properties occurring across the phase transition at 67 ºC. The initially amorphous VO2 thin films were fabricated by the emerging, Atomic Layer Deposition (ALD) technique with (tetrakis[ethylmethylamino]vanadium) {V(NEtMe)4} as precursor and H2O vapor as oxidation agent. For benchmarking we have also used the RF Magnetron Sputtering technique to deposit metallic vanadium thin films, which were later oxidized during furnace annealing. Post annealing of the as-deposited ALD films was performed in order to obtain the technologically important form of crystallized VO2 thin films using furnace annealing. All film depositions were carried out on native oxide covered (100) Si substrates. The conditions for successful furnace annealing are reported in terms of temperature and annealing gas composition and the physical characterization results are presented.
ALD of SrTiO3 and Pt for Pt/SrTiO3/Pt MIM Structures: Growth and Crystallization Study
Authors: Longo Valentino , Roozeboom F. , Kessels W.M.M. , Verheijen Marcel
Published: October 2013

Metal-insulator-metal (MIM) structures with ultrahigh-k strontium titanate films (SrTiO3, STO) and Pt as the dielectric and electrode material, respectively, have been prepared by ALD. The MIM structures were prepared with near-stoichiometric and Sr-rich ([Sr]/([Sr]+[Ti]) = 0.54 and 0.63, respectively) with a thickness of 15 nm. The influence of the rapid thermal annealing step at 600 °C in flowing N2, required to crystallize the STO, on the crystalline microstructure of the Pt bottom electrode and of the STO films has been investigated. Transmission electron microscopy and electron diffraction analysis evidenced that the morphology of the Pt bottom electrode is influenced by thermal treatment. Locally, an epitaxial relation between the <111> textured Pt and the STO film could be found. However, X-ray and electron diffraction analysis showed that the STO crystalline grains were mainly randomly oriented. Top view TEM analysis revealed that the near-stoichiometric STO thin films deposited on Pt have a crystallization behavior comparable to those deposited on Al2O3, with nano-crack formation at the grain boundaries and an average grain size of ~ 100 nm.
(Invited) ALD and Pulsed-CVD of Ru, RuO2, and SrRuO3
Authors: Han Jeong Hwan , Hwang Cheol Seong
Published: October 2013

Atomic layer deposition (ALD) and pulsed chemical vapor deposition (p-CVD) of Ru-based films, such as Ru, RuO2, and SrRuO3, were examined for their application to advanced dynamic random access memory capacitor with a design rule of < 20 nm. Growth characteristics and film properties of Ru grown by ALD and p-CVD using (DMPD)(EtCp)Ru and RuO4, respectively, were comparatively examined. Furthermore, deposition of RuO2 and SrRuO3 electrodes was explored by p-CVD and combined ALD/CVD processes using RuO4 and Sr(iPr3Cp)2 as Ru and Sr precursors, respectively. The leakage current density and equivalent oxide thickness of metal-insulator-metal capacitor, where Ru based electrodes and higher-k dielectrics were adopted, were also studied.
(Invited) Catalytic Surface Reactions during Nucleation and Growth of Atomic Layer Deposition of Noble Metals: A Case Study for Platinum
Authors: Mackus Adrie , Bol Ageeth , Kessels W. M. M.
Published: October 2013

Atomic layer deposition (ALD) of noble metals has attracted much attention in recent years for the deposition of thin metal films, as well as for the synthesis of supported metallic nanoparticles. Noble metal surfaces and nanoparticles possess catalytic activity for dissociation of metalorganic precursor and O2 molecules, which has important consequences for the reaction mechanisms of ALD. In this work, a case study is presented with respect to the importance of catalytic surface reactions during the nucleation and growth of Pt ALD, which serves as a model system for the growth of other noble metals by ALD. It is illustrated that atomic level understanding of these processes is vital for the development of novel nanopatterning and nanoparticle synthesis approaches.
Room Temperature Sensing of O2 and CO by Atomic Layer Deposition Prepared ZnO Films Coated with Pt Nanoparticles
Authors: Erkens Ivo , Blauw Michiel , Verheijen Marcel , Roozeboom F. , Kessels W. M. M.
Published: October 2013

Ultralow-power gas sensing devices need to operate without an energy consuming heater element. This requires the design of sensing devices that are so efficient that they can operate at room temperature (RT). Here, we report on the RT sensing performance of atomic layer deposition (ALD) prepared i-ZnO and Al-doped ZnO sensing devices. The sensitivity of these devices has been catalytically enhanced with ALD Pt nanoparticles (NPs). It was shown that the size distribution of the Pt NPs can be controlled by the number of Pt-ALD cycles. The Pt-enhanced sensing devices showed a reversible, proportional change in current response at RT upon exposure to O2 and CO. O2 could be detected, diluted in N2, down to 0.5%. CO could be detected, diluted in N2 in the presence of O2 and H2O, down to 20 ppm. Reference devices without Pt NPs showed no response, indicating the importance of the Pt NPs for the sensing mechanism.
(Invited) Characterization of Atomic Layer Deposited Films as Diffusion Barriers for Silver Art Objects
Authors: Marquardt Amy , Breitung E. M. , Drayman-Weisser T. , Gates G. , Rubloff G. W. , Phaneuf Ray J.
Published: October 2013

In this article we report on the characterization of atomic layer deposited (ALD) films on silver alloy objects, both with regard to film porosity, which potentially limits their effectiveness as tarnish barriers, and with regard to color change upon deposition, which affects their visual appearance. We find that the porosity of ALD alumina films decreases with thickness, and shows no clear dependence on surface preparation, nor on multiple ALD oxide layering. We also find that the optimized structures for minimizing color change are sensitive to the composition of the alloy, and must be tuned accordingly.
Construction of Hierarchically Structured TiO2 Nanotube Arrays for Efficient Dye-Sensitized Solar Cells
Authors: Ye M. , Zheng D. , Lv M. , Chen C. , Lin Z. , Lin Changjian
Published: October 2013

By subjecting vertically oriented TiO2 nanotube arrays fabricatedby electrochemical anodization to hydrothermal treatment,hierarchical structures composed of an underlayer of highlyordered anatase TiO2 nanotubes with small anatase and rutilenanocrystals emerged on the tube walls and a top layer of flowerlikestructures containing short rutile TiO2 nanorods were yielded.Remarkably, in sharp contrast to the dye-sensitized solar cells(DSSCs) prepared by using pure anatase TiO2 nanotubes asphotoanode, the devices produced by capitalizing on hierarchicallystructured nanotubes showed a significantly enhanced powerconversion efficiency PCE of 7.26%, which was attributed to thesynergy of larger surface area available for higher dye loading, theimproved light harvesting due to the efficient light scattering, andfast charge transport promoted by the heterojunctions betweenanatase and rutile phases.
Optimizing Light Harvesting and Charge Collection in Dye-Sensitized Solar Cells Based on ZnO
Authors: Pauporté Thierry
Published: October 2013

A large variety of ZnO structures have been prepared by sol-gel, electrodeposition and occlusion electrolysis for dye-sensitized solar cell (DSSC) application. The micro-/nanostructures include (nano)porous films, nanowire arrays and hierarchical structures. Several dyes (D149, D205, N719, Z907) have been tested. We have found that the best system is the nanoporous ZnO film prepared by electrodeposition using eosin Y as a structure directing agent and sensitized by the D149 indoline dye in the presence of octanoic acid. Electrochemical impedance spectroscopy (EIS) investigation of the cells’ functioning shows a high charge collection efficiency of the ZnO-based photoelectrodes (>92%). Combined with IPCE measurements, we conclude to a high charge injection efficiency (>95%). However, the cell optimizing must now focus on the light harvesting efficiency that must be increased by broadening the sunlight wavelength range collected at the ZnO-based photoelectrode.
Physical Characterization of Thin Films of CuxZnySz for Photovoltaic Applications
Authors: Di Benedetto Francesco , Cinotti Serena , Guerri Annalisa , De Luca Antonio , Lavacchi Alessandro , Montegrossi Giordano , Carlà Francesco , Felici Roberto , Innocenti Massimo
Published: October 2013

Kesterite, Cu2ZnSn(S,Se)4, are considered promising materials for energy conversion devices, encompassing reduced production costs and low environmental risks. The Electrochemical Atomic Layer Epitaxy (ECALE) method was used to obtain compound semiconductors, in the form of thin films, whose composition belongs to the compositional field of kesterite. Namely, CuxSy and CuxZnyS thin films were considered in this study. Films were characterised through Scanning Electron Microscopy, for film morphology, and X-ray Absorption Spectroscopy, to determine the structure of the film, the metal valence states, the nature of the coordinating ligand. In particular, films are found to always exhibit a Cu2-xS type structure, where Zn is likely tetrahedrally coordinated. The role of the two transition metal cations in modulating the overall properties of the thin layer results fundamental and it opens interesting perspectives in the chemical tuning of the photovoltaic properties.
Development of Amorphous Carbon-Based Variable Optical Gap Semiconductor Materials
Authors: Honda Kensuke , Yoshinaga Kohsuke , Nakahara Akira
Published: October 2013

Amorphous carbon (a-C) based semiconductor materials with variable optical gap and high semiconductor properties could be successfully fabricated by radio frequency plasma enhanced chemical vapor deposition (RF-PeCVD) method using a mixed solution of tetramethylsilane (TES) and 1,1,1,3,3,3-hexamethyldisilazane (HMDS) as a liquid source. The optical gap could be controlled by varying sizes and number of sp
2 clusters included in multi-phase structure of a-C by incorporating Si atoms. The resulting Si-doped a-C with 10 six-membered rings in sp
2 clusters shows 1.76 eV of optical gap and Si-doped a-C with 4 six-membered rings in sp
2 clusters shows 2.76 eV. From photocurrent measurement under UV exposure, it was clarified that these films functioned as high performance n-type semiconductors with ca. 4 % of quantum yield, which was on the same level as that obtained at anatase-type titanium oxide prepared by the sol-gel method.
Carboxy terminus and pore-forming domain properties specific to Cx37 are necessary for Cx37-mediated suppression of insulinoma cell proliferation
Authors: Nelson Tasha K. , Sorgen Paul L. , Burt Janis M.
Published: October 2013

Connexin 37 (Cx37) suppresses cell proliferation when expressed in rat insulinoma (Rin) cells, an effect also manifest in vivo during vascular development and in response to tissue injury. Mutant forms of Cx37 with nonfunctional channels but normally localized, wild-type carboxy termini are not growth suppressive. Here we determined whether the carboxy-terminal (CT) domain is required for Cx37-mediated growth suppression and whether the Cx37 pore-forming domain can be replaced with the Cx43 pore-forming domain and still retain growth-suppressive properties. We show that despite forming functional gap junction channels and hemichannels, Cx37 with residues subsequent to 273 replaced with a V5-epitope tag (Cx37–273tr*V5) had no effect on the proliferation of Rin cells, did not facilitate G1-cell cycle arrest with serum deprivation, and did not prolong cell cycle time comparably to the wild-type protein. The chimera Cx43*CT37, comprising the pore-forming domain of Cx43 and CT of Cx37, also did not suppress proliferation, despite forming functional gap junctions with a permselective profile similar to wild-type Cx37. Differences in channel behavior of both Cx37–273tr*V5 and Cx43*CT37 relative to their wild-type counterparts and failure of the Cx37-CT to interact as the Cx43-CT does with the Cx43 cytoplasmic loop suggest that the Cx37-CT and pore-forming domains are both essential to growth suppression by Cx37.