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Transparent and Flexible Thin-Film Transistors with High Performance Prepared at Ultralow Temperatures by Atomic Layer Deposition
摘要： High-performance, transparent, and flexible thin-film transistors (TFTs) with polycrystalline channels in a bottom-gate structure are successfully fabricated at extremely low temperatures of 80, 90, and 100 °C by atomic layer deposition (ALD) in which ZnO and Al2O3 are used as channels and dielectric layers, respectively. The transistors are superior to silicon-based TFTs in which high temperatures are necessarily involved in both preparation and postgrowth annealing. Among all devices, TFTs grown at 100 °C exhibit the best performance which can be attributed to the lowest grain boundary trap density. Additionally, the TFTs are successfully transferred to plastic substrates without any performance degradation, which shows a high mobility of 37.1 cm2 V?1 s?1, a high on/off-state current ratio of 107 at VDS = 0.1 V, a small subthreshold swing of 0.38 V dec?1, and a proper threshold voltage of 1.34 V as well as an excellent bias stability.
关键词： bottom gate/top contacts,thin-film transistors,oxide,atomic layer deposition,zinc oxide,aluminum
更新于2025-09-10 09:29:36
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Temperature dependent electrical characteristics of rectifying graphitic contacts to p-type silicon
摘要： Graphitic contacts to semiconductors have been shown to provide highly rectifying current-voltage characteristics coupled with high thermal/chemical stability. Energetically deposited graphitic contacts to p-type Si have exhibited rectification ratios (at ± 1.0 V) up to 106:1 and ideality factors approaching unity. Here, we report temperature dependent current-voltage (I-V-T) measurements performed on such devices. The measurements and subsequent analysis show that during energetic carbon deposition, deleterious oxide/contaminants are removed from the Si substrate surface. The Richardson constant of the p-type Si extracted from the I-V-T measurements agrees with the theoretical value, indicating that the surface contaminants are removed without significant damage to the underlying Si. Therefore, by energetic deposition of C on Si, C-Si junctions can be formed with low lateral inhomogeneity and low interface defect density. These attributes of the junctions enable the observed near-ideal Schottky diode characteristics.
关键词： graphenic carbon,electronic materials,graphitic carbon,Schottky contacts
更新于2025-09-10 09:29:36
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[Nanostructure Science and Technology] Nanowire Electronics || Metal-Semiconductor Compound Contacts to Nanowire Transistors
摘要： Semiconductor nanowires [1–4] are promising building blocks for next-generation ultrascaled devices for electronic [5–7] and optoelectronic [8–10] applications. An important aspect for the development, maturity, and ef?ciency of these ultrascaled devices is the detailed understanding of and control over the phase transformation that accompanies the formation of their compound contacts for lithography-free self-aligned gate design [11, 12]. The term “compound” here refers to the formed phases that have ?xed stoichiometry between metal and semiconductor elements, to be distinguished from the broader “alloy” term for phases that may include nonstoichiometric or amorphous structure. This distinction is important because the formation of a low resistance, crystalline, and thermally stable compound contact is most preferred for realizing reliable functionality in ultrascaled semiconductor transistors. Usually, the phase of compound contact and its interfacial property with semiconductor nanowire (NW) can largely affect the band alignment and charge injection in NW channels. This demands the detailed studies of the metal-semiconductor solid-state reactions, including the formed compound phases, reaction kinetics, and their correlation to the device performances. In this book chapter, we provide a thorough discussion of these three topics.
关键词： metal-semiconductor solid-state reactions,compound contacts,reaction kinetics,phase transformation,Semiconductor nanowires,device performances
更新于2025-09-10 09:29:36
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Gallium Oxide || Schottky contacts to β-Ga2O3
摘要： The success of β-Ga2O3 as the wide-bandgap semiconductor platform for ultrahigh efficiency electronic and optoelectronic devices relies on the ability to control the properties of ohmic and rectifying, or Schottky, contacts on this material. This chapter focuses on the current status of research and development of Schottky contacts on β-Ga2O3: the materials and structures used and their corresponding electrical properties.
关键词： Schottky contacts,β-Ga2O3,electronic devices,optoelectronic devices,wide-bandgap semiconductor
更新于2025-09-10 09:29:36
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Temperature-dependent interface stability of MoO <sub/>3</sub> /GaAs(001) hybrid structures
摘要： We report on the influence of growth temperature and post-growth annealing on interface formation and film structure of thin MoO3 films on GaAs(001), which plays an important role for a future application as carrier-selective contacts or diffusion barriers in III/V-semiconductor spin- and opto-electronics or photovoltaics. Growth and post-growth annealing were performed in a manner that emulates heterostructure growth and lithographic processing. High-resolution transmission electron microscopy reveals nanocrystalline (“amorphous”) growth at temperatures up to 200 °C and a transition to polycrystalline growth at about 400 °C. Spatially resolved chemical analysis by energy dispersive x-ray spectroscopy reveals strong intermixing at the MoO3/GaAs(001) interface proceeding during both film deposition and annealing. Our results evidence the important role of intermixing occurring during the process of interface formation at the very beginning of deposition.
关键词： intermixing,temperature-dependent,interface stability,GaAs(001),diffusion barriers,MoO3,carrier-selective contacts
更新于2025-09-10 09:29:36
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Gallium Oxide || Ohmic contacts to gallium oxide
摘要： The deposition of a metal onto a semiconductor surface to provide low contact resistance, high-reliability electrical contacts without adversely affecting the device during the metallization process is one of the most important challenges in device fabrication. Consequently, a fundamental understanding of how contacts work is essential for successful device manufacturing and commercialization. The physics of carrier transport across the metal-semiconductor junction renders metal contacts either rectifying (a.k.a. Schottky) or nonrectifying. A nonrectifying contact whose relationship between current and voltage has a low interfacial contact resistance Rc, and is preferably linear, is referred to as an Ohmic contact. Achieving low contact resistance Rc (Ω mm) or contact resistivity ρc (Ω cm2) has required a great amount of investigation for every relevant semiconductor material in the past. Typically, the successful formation of an Ohmic contact has relied on three constituent requirements: highly or degenerately doped semiconductor, choice of metallization, and thermal annealing. In the case of silicon, for instance, diffusion processes have been the topic of much early work but ultimately the control and reproducibility of ion implantation have rendered it an industry standard. For compound semiconductor heterostructure devices based on GaAs or GaN, the presence of a two-dimensional electron gas (2DEG) has necessitated a multilayer metallization deposition and annealing scheme, the details of which took many years to optimize. Particularly in the case of III-nitride high electron mobility transistors (HEMTs), Ohmic contacts were relatively easy to make on heteroepitaxal GaN due to its high dislocation density as the barrier height was reduced through defect-assisted formation of metal-nitride alloys during the anneal. Subsequent breakthroughs in GaN crystal growth, however, resulted in several orders of magnitude lower dislocation density homoepitaxial GaN, and naturally the contact resistance obtained under identical process conditions was higher [1]. Regrowth techniques to provide n+-doped GaN have become commonplace as a result.
关键词： thermal annealing,semiconductor,metallization,gallium oxide,contact resistance,Ohmic contacts
更新于2025-09-09 09:28:46
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Indium-Gallium-Zinc-Oxide Schottky Synaptic Transistors for Silent Synapse Conversion Emulation
摘要： Silent synapses play an important role in synaptic plasticity and the nervous system development. In this letter, indium-gallium-zinc-oxide (IGZO) Schottky electric-double-layer transistors were proposed for silent synapse conversion emulation. Silent to active conversion of such neuromorphic devices was realized by applying voltage pulses on the gate electrode of the synaptic transistor. In addition, some important synaptic behaviors such as paired-pulse facilitation and dynamic high-pass filtering were also emulated in the IGZO-based Schottky synaptic transistor after electric pulse activation.
关键词： Electric-double-layer transistors,IGZO,Neuromorphic devices,Schottky contacts
更新于2025-09-09 09:28:46
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Low-Voltage Operating Single-Wall Carbon Nanotube Thin-Film Transistors Using High Work Function Contacts on Flexible Substrates
摘要： There have been constant attempts as regards high-performance thin-film transistors (TFTs) by improving the charge injection between the source/drain electrode (S/D) and the channel. In this paper, we investigate the effect of the electric contact on the device performance of single-wall carbon nanotube (SWCNT) TFTs employing the suitable work function material. In order to realize the electric contacts for the dominant hole injection between the S/D and the SWCNT active channel, a high work function material of molybdenum trioxide (MoOx) fabricated by an optimized process are utilized. The contact resistance is extracted by plotting the width-normalized resistance of SWCNT-TFT with Pd and MoOx contacts as a function of channel length. We also demonstrate low-voltage operating SWCNT TFTs on flexible polyimide substrates with the reduced electric contacts. Without a buffer film which has been widely used to improve the device performance of TFT on a flexible substrate, high-performance low-voltage operating SWCNT-TFTs were achieved.
关键词： Flexible Substrate,Charge Injection,Device Performance,High Work Function Contacts,SWCNT TFTs
更新于2025-09-04 15:30:14
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Suppression of segregation of the phosphorus δ-doping layer in germanium by incorporation of carbon
摘要： The successful formation of abrupt phosphorus (P) δ-doping profiles in germanium (Ge) is reported. When the P δ-doping layers were grown by molecular beam epitaxy (MBE) directly on Ge wafers whose surfaces had residual carbon impurities, more than a half the phosphorus atoms were confined successfully within a few nm of the initial doping position even after the growth of Ge capping layers on the top. On the other hand, the same P layers grown on Ge buffer layers that had much less carbon showed significantly broadened P concentration profiles. Current–voltage characteristics of Au/Ti/Ge capping/P δ-doping/n-Ge structures having the abrupt P δ-doping layers with carbon assistance showed excellent ohmic behaviors when P doses were higher than 1 × 1014 cm?2 and the capping layer thickness was as thin as 5 nm. Therefore, the insertion of carbon around the P doping layer is a useful way of realizing ultrashallow junctions in Ge.
关键词： germanium,carbon incorporation,molecular beam epitaxy,ohmic contacts,phosphorus δ-doping
更新于2025-09-04 15:30:14
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Approaching 23% with large‐area monoPoly cells using screen‐printed and fired rear passivating contacts fabricated by inline PECVD
摘要： We present n‐type bifacial solar cells with a rear interfacial SiOx/n+:poly‐Si passivating contact (‘monoPoly’ cells) where the interfacial oxide and n+:poly‐Si layers are fabricated using an industrial inline plasma‐enhanced chemical vapor deposition (PECVD) tool. We demonstrate outstanding passivation quality with dark saturation current density (J0) values of approximately 3 fA/cm2 and implied open‐circuit voltage (iVoc) of 730 mV at 1‐sun conditions after firing in an industrial belt furnace. Using a simple solar cell process flow that can be easily adapted for mass production, a peak cell efficiency of 22.8% with a cell open circuit voltage (Voc) of 696 mV is achieved on large‐area, screen‐printed, Czochralski‐silicon (Cz‐Si) solar cells using commercial fire‐through metal pastes.
关键词： silicon wafer,screen‐printed,industrial process,passivated contacts,industrial firing,PECVD,solar cells,large‐area
更新于2025-09-04 15:30:14