BIPOLAR THEORY OF METAL–SEMICONDUCTOR CONTACTS UNDER ARBITRARY INJECTION LEVELS

1963 ◽  
Vol 41 (7) ◽  
pp. 1010-1021
Author(s):  
R. E. Horita ◽  
R. E. Burgess
Keyword(s):  
Ohmic Contact ◽  
Hole Mobility ◽  
Current Theory ◽  
Electron Current ◽  
Theoretical Limit ◽  
Current Ratio ◽  
One Dimensional ◽  
High Injection ◽  
Semiconductor Contacts ◽  
Hole Current

Metal–semiconductor contacts have been known empirically to obey a modified diode equation I = Is (exp qV/akT −1), where the parameter a often took values greater than the theoretical limit of two. Previous theories could not simply account for this anomaly. The model presented in this paper considers one-dimensional bipolar flow of carriers with zero recombination in a homogeneous semiconductor filament with a rectifying and an ohmic contact at opposite ends. The zero-electron-current theory by Borneman et al. (1955), valid for low injection levels, is extended to arbitrary injection levels by the use of the Misawa junction relations (1955). Then the nonzero-electron-current theory is developed. This theory shows that a is unity for low injection into extrinsic semiconductors and that a = (3b − M)/(b − M) for arbitrary injection into intrinsic semiconductors and for high injection into extrinsic semiconductors; M is the electron-to-hole current ratio and b is the electron-to-hole mobility ratio. Thus a can take any value depending on the magnitude of M/b.

scholarly journals Melt Blown Fiber-Assisted Solvent-Free Device Fabrication at Low-Temperature

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1091
Author(s):  
Minjong Lee ◽  
Joohoon Kang ◽  
Young Tack Lee
Keyword(s):  
Transition Metal Dichalcogenides ◽  
Hole Mobility ◽  
Device Fabrication ◽  
Solvent Free ◽  
Oxide Semiconductor ◽  
Drain Voltage ◽  
Cmos Inverter ◽  
Current Ratio ◽  
Metal Dichalcogenides ◽  
P Type

In this paper, we propose a solvent-free device fabrication method using a melt-blown (MB) fiber to minimize potential chemical and thermal damages to transition-metal-dichalcogenides (TMDCs)-based semiconductor channel. The fabrication process is composed of three steps; (1) MB fibers alignment as a shadow mask, (2) metal deposition, and (3) lifting-up MB fibers. The resulting WSe2-based p-type metal-oxide-semiconductor (PMOS) device shows an ON/OFF current ratio of ~2 × 105 (ON current of ~−40 µA) and a remarkable linear hole mobility of ~205 cm2/V·s at a drain voltage of −0.1 V. These results can be a strong evidence supporting that this MB fiber-assisted device fabrication can effectively suppress materials damage by minimizing chemical and thermal exposures. Followed by an MoS2-based n-type MOS (NMOS) device demonstration, a complementary MOS (CMOS) inverter circuit application was successfully implemented, consisted of an MoS2 NMOS and a WSe2 PMOS as a load and a driver transistor, respectively. This MB fiber-based device fabrication can be a promising method for future electronics based on chemically reactive or thermally vulnerable materials.

Ambipolar Thin-Film Transistors Fabricated by PECVD Nanocrystalline Silicon

2006 ◽  
Vol 910 ◽  
Author(s):  
Czang-Ho Lee ◽  
Andrei Sazonov ◽  
Mohammad R. E. Rad ◽  
G. Reza Chaji ◽  
Arokia Nathan
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Field Effect ◽  
Chemical Vapor ◽  
Hole Mobility ◽  
Complementary Metal Oxide Semiconductor ◽  
Nanocrystalline Silicon ◽  
Oxide Semiconductor ◽  
Hole Injection ◽  
Current Ratio

AbstractWe report on directly deposited plasma-enhanced chemical vapor deposition (PECVD) nanocrystalline silicon (nc-Si:H) ambipolar thin-film transistors (TFTs) fabricated at 260 °C. The ambipolar operation is achieved adopting Cr metal contacts with high-quality nc-Si:H channel layer, which creates highly conductive Cr silicided drain/source contacts, reducing both electron and hole injection barriers. The n-channel nc-Si:H TFTs show a field-effect electron mobility (meFE) of 150 cm2/Vs, threshold voltage (VT) ~ 2 V, subthreshold slope (S) ~0.3 V/dec, and ON/OFF current ratio of more than 107, while the p-channel nc-Si:H TFTs show a field-effect hole mobility (mhFE) of 26 cm2/Vs, VT ~ -3.8 V, S ~0.25 V/dec, and ON/OFF current ratio of more than 106. Complementary metal-oxide-semiconductor (CMOS) logic integrated with two ambipolar nc-Si:H TFTs shows reasonable transfer characteristics. The results presented here demonstrate that low-temperature nc-Si:H TFT technology is feasible for total integration of active-matrix TFT backplanes.

Effects of Electron Current and Hole Current on Dielectric Breakdown in HfSiON Gate Stacks

2012 ◽  
Vol 51 (4R) ◽  
pp. 041105
Author(s):  
Izumi Hirano ◽  
Takeshi Yamaguchi ◽  
Yasushi Nakasaki ◽  
Ryosuke Iijima ◽  
Katsuyuki Sekine ◽  
...  
Keyword(s):  
Dielectric Breakdown ◽  
Electron Current ◽  
Gate Stacks ◽  
Hole Current

New insight into intramolecular conjugation in the design of efficient blue materials: from the control of emission to absorption

2017 ◽  
Vol 5 (25) ◽  
pp. 6185-6192 ◽  
Author(s):  
Jie Yang ◽  
Qingxun Guo ◽  
Zichun Ren ◽  
Xuming Gao ◽  
Qian Peng ◽  
...  
Keyword(s):  
Hole Mobility ◽  
Theoretical Limit ◽  
Insight Into

Three blue luminogens of Cz-3tPE, TPA-3TPP and Cz-3TPP, have been successfully designed, in which, Cz-3TPP shows a high hole mobility of 0.83 × 10−3 cm2 V−1 s−1 and the best EL performance with EQE up to 4.27% at 397 nm, approaching the theoretical limit.

Rectifying and Schottky characteristics of a-SixGe1−xOy with metal contacts

2014 ◽  
Vol 92 (7/8) ◽  
pp. 606-610 ◽  
Author(s):  
Md Muztoba ◽  
Mukti Rana
Keyword(s):  
Ohmic Contact ◽  
Infrared Detector ◽  
Schottky Contact ◽  
Thermionic Emission ◽  
Emission Model ◽  
Metal Contacts ◽  
Temperature Changes ◽  
Barrier Heights ◽  
Current Voltage ◽  
Semiconductor Contacts

Metal–semiconductor contacts are a vital part of semiconductor devices as they can form a Schottky barrier or an Ohmic contact. The nature of the contact plays an important role in determining the electrical and physical characteristics of the device and hence is of paramount importance in the operation of the device. In the current work we report the design, fabrication, and current–voltage (I-V) characteristics of microbolometers, a type of infrared detector where the change in temperature changes the resistance of the sensing layer. Eight different types of microbolometers were fabricated using a-SixGe1−x or a-SixGe1−xOy sensing layers and Ti, Cr, Al, Au, Ni, or Ni0.80Cr0.20 metals contacts. It has been observed that bolometers with an a-Si0.15Ge0.85 (Si was lightly p-doped) sensing layer formed a Schottky contact with Ti, Au, Cr, and Al contact metals, while bolometers with a-Si0.15Ge0.85 (Si was heavily n-doped) sensing layers formed an Ohmic contact with Au. For microbolometers with a Si0.15Ge0.85O0.039 sensing layer, both Ni and Ni0.80Cr0.20 contact metals formed the Ohmic contact. For a-SixGe1−x and a-SixGe1−xOy microbolometers, Au and Ni0.80Cr0.20 were used as the absorber layers, respectively. The I–V characteristics of the microbolometers were analyzed with a thermionic emission model. A linear dependence on the Ge composition was approximated to find the effective Richardson constant. The theory predicts Richardson constants of 112 and 50 A/cm2K2 for Si and Ge, respectively. Barrier heights of all devices are calculated and the reasons for the formation of the Ohmic and Schottky contacts are discussed.

scholarly journals Self-aligned double injection-function contact mitigating short channel effects in sub-micron channels of solution processed indium gallium zinc oxide

2021 ◽  
Author(s):  
Gil Sheleg ◽  
Nir Tessler
Keyword(s):  
Ohmic Contact ◽  
Thin Film Transistor ◽  
Short Channel Effects ◽  
Short Channel ◽  
Solution Processed ◽  
Double Injection ◽  
High Injection ◽  
Channel Effects ◽  
Injection Barrier ◽  
Injection Function

Abstract We propose and demonstrate self-aligned Double Injection Function Thin Film Transistor (DIF-TFT) architecture that mitigates short channel effects in 200nm channel on a non-scaled insulator (100nm SiO2). In this conceptual design, a combination of an ohmic-like injection contact and a high injection-barrier metal allows maintaining the high ON currents while suppressing the drain-induced barrier lowering. Using an industrial 2D device simulator (Sentaurus), we propose two methods to realize the DIF concept and we use one of them to experimentally demonstrate a DIF-TFT based on solution processed IGZO. Using molybdenum as the ohmic contact and platinum as the high injection barrier, we compare three transistor’s source-contacts: ohmic, Schottky, and double injection function. The fabricated DIF-TFT exhibits saturation at sub 1V drain bias with only about a factor of 2 loss in ON current compared to the ohmic contact.

Characteristics of Vertical Carbon Nanotube Field-Effect Transistors on p-GaAs

2019 ◽  
Vol 11 (9) ◽  
pp. 1239-1246
Author(s):  
Jingqi Li ◽  
Xiaofeng Chen ◽  
Gheorghe Iordache ◽  
Nini Wei ◽  
Husam N. Alshareef
Keyword(s):  
Carbon Nanotube ◽  
Doping Level ◽  
Field Effect Transistors ◽  
Electron Current ◽  
Drain Voltage ◽  
Single Walled Carbon Nanotube ◽  
Drain Side ◽  
Calculation Results ◽  
Hole Current ◽  
The Impact

A semiclassical method is used to simulate the characteristics of vertical carbon nanotube fieldeffect transistors on p-GaAs. The calculation results show unique transfer characteristics that depend on the sign of the drain voltage. The transistors exhibit p-type characteristics and ambipolar characteristics for a positive drain voltage and a negative drain voltage, respectively. The p-type characteristics do not change with the GaAs bandgap and doping level, because the hole current from the single-walled carbon nanotube (SWCNT) and drain side dominates the whole current. In contrast, the ambipolar characteristics are greatly influenced by the GaAs bandgap and doping level. Only the electron current in the ambipolar characteristics increases as the GaAs bandgap decreases. Increasing the p-type doping of GaAs increases the p-branch current and decreases the electron current (n-branch) of the ambipolar characteristics. The effects of the SWCNT bandgap and doping level are different from those of GaAs, and the impact of SWCNT on the p-type characteristics is much greater than the impact on the ambipolar characteristics. The p-type current increases as the SWCNT bandgap decreases.

Charge Carrier Transport in a-Si:H/a-SiC:H Heterojunction with Blocking Layer

2001 ◽  
Vol 685 ◽  
Author(s):  
Yu. Vygranenko ◽  
M. Fernandes ◽  
P. Louro ◽  
A. Mačarico ◽  
M. Vieira
Keyword(s):  
Charge Carrier ◽  
Carrier Transport ◽  
Short Circuit ◽  
Free Carrier ◽  
Charge Carrier Transport ◽  
Blocking Layer ◽  
One Dimensional ◽  
Current Densities ◽  
Hole Current ◽  
Carrier Population

AbstractThis paper presents a one-dimensional numerical simulation of the charge carrier transport and photogeneration within a p-i-n (a-Si:H) homojunction and a p(a-SiC:H)/i (a-Si:H)/n (a-SiC:H) heterojunction with weakly-doped n-layers. A good matching between the simulated J-V characteristics and the corresponding experimental curves has been achieved for both configurations. By analysing the simulated band diagrams, electric fielddistributions, the electron and hole current densities, and the free carrier population profiles we conclude that in short-circuit mode the carrier transport is different in the homojunction and heterojunction due to band offsets.

scholarly journals A Universal Method to Weld Individual One-Dimensional Nanostructures with a Tungsten Needle Based on Synergy of the Electron Beam and Electrical Current

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 469
Author(s):  
Peng Zhao ◽  
Yu Zhang ◽  
Shuai Tang ◽  
Runze Zhan ◽  
Juncong She ◽  
...  
Keyword(s):  
Electron Beam ◽  
Ohmic Contact ◽  
Welded Joints ◽  
Electrical Current ◽  
Universal Method ◽  
One Dimensional ◽  
1D Nanostructures ◽  
1D Nanostructure ◽  
Tungsten Needle

One-dimensional (1D) nanostructures are extensively used in the design of novel electronic devices, sensors, and energy devices. One of the major challenges faced by the electronics industry is the problem of contact between the 1D nanostructure and electrode, which can limit or even jeopardize device operations. Herein, a universal method that can realize good Ohmic and mechanical contact between an individual 1D nanostructure and a tungsten needle at sub-micron or micron scale is investigated and presented in a scanning electron microscope (SEM) chamber with the synergy of an electron beam and electrical current flowing through the welded joint. The linear I‒V curves of five types of individual 1D nanostructures, characterized by in-situ electrical measurements, demonstrate that most of them demonstrate good Ohmic contact with the tungsten needle, and the results of in-situ tensile measurements demonstrate that the welded joints possess excellent mechanical performance. By simulation analysis using the finite element method, it is proved that the local heating effect, which is mainly produced by the electrical current flowing through the welded joints during the welding process, is the key factor in achieving good Ohmic contact.

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