scholarly journals Impact of n-Doping Mechanisms on the Molecular Packing and Electron Mobilities of Molecular Semiconductors for Organic Thermoelectrics

2022 ◽  
Author(s):  
Yan Zeng ◽  
Guangchao Han ◽  
Yuanping Yi
Keyword(s):  
Charge Transfer ◽  
Carrier Concentration ◽  
Organic Semiconductors ◽  
Electron Mobility ◽  
Molecular Packing ◽  
High Electron ◽  
Mobility Of Charge Carriers ◽  
N Doping ◽  
Molecular Semiconductor ◽  
The Impact

Electrical conductivity is one of the key parameters for organic thermoelectrics and depends on both the concentration and mobility of charge carriers. To increase the carrier concentration, molecular dopants have to be added into organic semiconductor materials, whereas the introduction of dopants can influence the molecular packing structures and hence carrier mobility of the organic semiconductors. Herein, we have theoretically investigated the impact of different n-doping mechanisms on molecular packing and electron transport properties by taking N-DMBI-H and Q-DCM-DPPTT respectively as representative n-dopant and molecular semiconductor. The results show that when the doping reactions and charge transfer spontaneously occur in the solution at room temperature, the oppositely charged dopant and semiconductor molecules will be tightly bound to disrupt the semiconductor to form long-range molecular packing, leading to a substantial decrease of electron mobility in the doped film. In contrast, when the doping reactions and charge transfer are activated by heating the doped film, the molecular packing of the semiconductor is slight affected and hence the electron mobility remains quite high. This work indicates that thermally-activated n-doping is an effective way to achieve both high carrier concentration and high electron mobility in n-type organic thermoelectric materials.

6,6′-Diaryl-substituted biazulene diimides for solution-processable high-performance n-type organic semiconductors

2018 ◽  
Vol 2 (5) ◽  
pp. 975-985 ◽  
Author(s):  
Hanshen Xin ◽  
Jing Li ◽  
Congwu Ge ◽  
Xiaodi Yang ◽  
Tianrui Xue ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Electron Mobility ◽  
High Performance ◽  
Molecular Packing ◽  
High Electron ◽  
High Electron Mobility ◽  
Dipolar Moment ◽  
Solution Processable

High electron mobility derived from dense molecular packing induced by the dipolar moment of azulene units.

The AlInGaN back barrier effect on DC characteristics of AlGaN/GaN high electron mobility transistor

2019 ◽  
Vol 33 (18) ◽  
pp. 1950190
Author(s):  
Hai Li Wang ◽  
Peng Yang ◽  
Kun Xu ◽  
Xiang Yang Duan ◽  
Shu Xiang Sun
Keyword(s):  
Mole Fraction ◽  
Electron Mobility ◽  
Transport Model ◽  
High Electron Mobility Transistors ◽  
High Electron Mobility Transistor ◽  
High Electron ◽  
High Electron Mobility ◽  
Conduction Band Offset ◽  
Electron Mobility Transistors ◽  
The Impact

In this paper, we investigated the impact of thickness and mole fraction AlInGaN back barrier on the DC performance of AlGaN/GaN high electron mobility transistors (HEMTs) by numerical simulation. The simulations are performed using the hydrodynamic transport model (HD). The simulation results indicated that an inserted AlInGaN back barrier with increasing thickness and mole fraction could effectively confine the electron in the channel, resulting in a significant improvement of the channel current and transconductance. Additionally, the variation of conduction band offset and the increase of total number electron in the channel led to the threshold voltage moving toward a more negative value.

N- and P-Type Building Blocks for Organic Electronics Based on Oligothiophene Cores

2003 ◽  
Vol 771 ◽  
Author(s):  
Antonio Facchetti ◽  
Myung-Han Yoon ◽  
Howard E. Katz ◽  
Melissa Mushrush ◽  
Tobin J. Marks
Keyword(s):  
Organic Semiconductors ◽  
Organic Electronics ◽  
Carrier Mobility ◽  
Building Blocks ◽  
Molecular Packing ◽  
Conjugation Length ◽  
Π Interactions ◽  
P Type ◽  
The Impact ◽  
Homo Lumo

AbstractOrganic semiconductors exhibiting complementary-type carrier mobility are the key components for the development of the field of “gplastic electronics” We present here a novel series of α,ω- and isomerically pure ββ'-diperfluorohexyl-substituted thiophene and study the impact of fluoroalkyl substitution and conjugation length vis-a-vis the corresponding fluorinefree analogues. Trends between the fluorinated and fluorine-free families in molecular packing, HOMO-LUMO gap, and π-π interactions are found to be strikingly similar. TFT measurements indicate that all members of the fluorinated series are n-type semiconductors

scholarly journals Channel Characteristics of InAs/AlSb Heterojunction Epitaxy: Comparative Study on Epitaxies with Different Thickness of InAs Channel and AlSb Upper Barrier

Coatings ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 318 ◽  
Author(s):  
He Guan ◽  
Shaoxi Wang ◽  
Lingli Chen ◽  
Bo Gao ◽  
Ying Wang ◽  
...  
Keyword(s):  
Barrier Layer ◽  
Electron Mobility ◽  
High Electron Mobility Transistors ◽  
Electron Velocity ◽  
High Electron ◽  
High Electron Mobility ◽  
Electron Mobility Transistors ◽  
Channel Thickness ◽  
The Impact ◽  
Different Thickness

Because of the high electron mobility and electron velocity in the channel, InAs/AlSb high electron mobility transistors (HEMTs) have excellent physical properties, compared with the other traditional III-V semiconductor components, such as ultra-high cut-off frequency, very low power consumption and good noise performance. In this paper, both the structure and working principle of InAs/AlSb HEMTs were studied, the energy band distribution of the InAs/AlSb heterojunction epitaxy was analyzed, and the generation mechanism and scattering mechanism of two-dimensional electron gas (2DEG) in InAs channel were demonstrated, based on the software simulation in detail. In order to discuss the impact of different epitaxial structures on the 2DEG and electron mobility in channel, four kinds of epitaxies with different thickness of InAs channel and AlSb upper-barrier were manufactured. The samples were evaluated with the contact Hall test. It is found the sample with a channel thickness of 15 nm and upper-barrier layer of 17 nm shows a best compromised sheet carrier concentration of 2.56 × 1012 cm−2 and electron mobility of 1.81 × 104 cm2/V·s, and a low sheet resistivity of 135 Ω/□, which we considered to be the optimized thickness of channel layer and upper-barrier layer. This study is a reference to further design InAs/AlSb HEMT, by ensuring a good device performance.

scholarly journals High electron mobility and low carrier concentration of hydrothermally grown ZnO thin films on seeded a-plane sapphire at low temperature

2015 ◽  
Vol 10 (1) ◽  
Author(s):  
Nurul Azzyaty Jayah ◽  
Hafizal Yahaya ◽  
Mohamad Rusop Mahmood ◽  
Tomoaki Terasako ◽  
Kanji Yasui ◽  
...  
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Carrier Concentration ◽  
Electron Mobility ◽  
Zno Thin Films ◽  
High Electron ◽  
High Electron Mobility

A Charge Storage Based Enhancement Mode AlGaN/GaN High Electron Mobility Transistor

2018 ◽  
Vol 913 ◽  
pp. 870-875 ◽  
Author(s):  
Hui Wang ◽  
Ling Li Jiang ◽  
Ning Wang ◽  
Hong Yu Yu ◽  
Xin Peng Lin
Keyword(s):  
Electron Mobility ◽  
Gate Dielectric ◽  
High Electron Mobility Transistor ◽  
Charge Storage ◽  
High Electron ◽  
High Electron Mobility ◽  
Charge Trap ◽  
Enhancement Mode ◽  
A Charge ◽  
The Impact

In this work, a charge storage based enhancement mode (E-mode) AlGaN/GaN high electron mobility transistor (HEMT) is proposed and studied. A stacked gate dielectrics, consisting of a tunnel oxide, a charge trap layer and a blocking oxide are applied in the HEMT structure. The E-mode can be realized by negative charge storage within the charge trap layer during the programming process. The impact of the programming condition and the thickness of the dielectrics on the threshold voltage (Vth) are simulated systematically. It is found that the Vth increases with the increasing programming voltage and time due to the increase of the storage charge. Under proper programming condition, the Vth can be increased to more than 2 V. Moreover, It is also found that the Vth increases with the decrease of the thickness of the dielectrics. In addition, it is found that the breakdown voltage of such HEMT can be adjusted by varying the gate dielectric stacks.

scholarly journals Tuning of Molecular Electrostatic Potential Enables Efficient Charge Transport in Crystalline Azaacenes: A Computational Study

2020 ◽  
Author(s):  
Andrey Sosorev ◽  
Dmitry Dominskiy ◽  
Ivan Chernyshov ◽  
Roman Efremov
Keyword(s):  
Organic Semiconductors ◽  
Electrostatic Potential ◽  
Rational Design ◽  
Molecular Electrostatic Potential ◽  
Computational Study ◽  
High Mobility ◽  
Molecular Packing ◽  
Frontier Molecular Orbital ◽  
Charge Mobility ◽  
The Impact

Chemical versatility of organic semiconductors provides nearly unlimited opportunities for tuning their electronic properties. However, despite decades of research, relationship between molecular structure, molecular packing and charge mobility in these materials remains poorly understood. This reduces the search for high-mobility organic semiconductors to the inefficient trial-and-error approach. For clarifying the abovementioned relationship, investigations of the effect of small changes in the chemical structure on OSs properties are particularly important. In this study, we address computationally the impact of substitution of C-H atom pairs by nitrogen atoms (N-substitution) on molecular properties, molecular packing and charge mobility of crystalline oligoacenes. Besides of decreasing frontier molecular orbital levels, N-substitution dramatically alters molecular electrostatic potential yielding pronounced electron-rich and electron-deficient areas. These changes in the molecular electrostatic potential strengthen face-to-face and edge-to-edge interactions in the corresponding crystals and result in the crossover from the herringbone packing motif to π-stacking. When the electron-rich and electron-deficient areas are large, sharply defined and, probably, have certain symmetry, charge mobility increases up to 3-4 cm2V-1s-1. The results obtained highlight the potential of azaacenes for application in organic electronic devices and are expected to facilitate rational design of organic semiconductors for steady improvement of organic electronics.

scholarly journals Improving Transport Properties of GaN-Based HEMT on Si (111) by Controlling SiH4 Flow Rate of the SiNx Nano-Mask

Coatings ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 16
Author(s):  
Jin-Ji Dai ◽  
Cheng-Wei Liu ◽  
Ssu-Kuan Wu ◽  
Sa-Hoang Huynh ◽  
Jhen-Gang Jiang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Electron Mobility ◽  
Chemical Vapor ◽  
High Electron Mobility Transistor ◽  
Threading Dislocation ◽  
High Electron ◽  
Threading Dislocation Density ◽  
Dimensional Electron Gas ◽  
Short Time ◽  
The Impact

The AlGaN/AlN/GaN high electron mobility transistor structures were grown on a Si (111) substrate by metalorganic chemical vapor deposition in combination with the insertion of a SiNx nano-mask into the low-temperature GaN buffer layer. Herein, the impact of SiH4 flow rate on two-dimensional electron gas (2DEG) properties was comprehensively investigated, where an increase in SiH4 flow rate resulted in a decrease in edge-type threading dislocation density during coalescence process and an improvement of 2DEG electronic properties. The study also reveals that controlling the SiH4 flow rate of the SiNx nano-mask grown at low temperatures in a short time is an effective strategy to overcome the surface desorption issue that causes surface roughness degradation. The highest electron mobility of 1970 cm2/V·s and sheet carrier concentration of 6.42 × 1012 cm−2 can be achieved via an optimized SiH4 flow rate of 50 sccm.

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