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81.
利用超快光谱技术系统研究了在丁胺包裹的CdSe量子点敏化的TiO2纳米晶薄膜起始时刻界面间电子转移动力学。与之前的报道不同,该实验结果表明:CdSe量子点经过表面修饰后,两相电子注入机制--热电子和冷电子注入得以被证实,即:电子能分别从CdSe量子点导带中高的振动能级和导带底转移到TiO2的导带。该机制详细描绘了电子在纳米界面间转移的图景。进一步研究发现:热电子注入的电子耦合强度(3.6±0.1 meV)比弛豫后的基态电子注入高两个数量级,基于Marcus理论,伴随着0.083 eV的重组能,冷电子注入的耦合强度值为~50 μeV。 相似文献
82.
The properties of AlxGa1−xN/GaN high electron mobility transistor (HEMT) impacted by pressure are characterized quantitatively. The results indicate that the dislocation density increases as the critical thickness decreases with increasing pressure. The two-dimensional electron gas density was found to be linearly changeable with the pressure. A simulation has been completed to verify the influence of electron mobility. The results show that the misfit dislocation scattering induced by the pressure is a major limiting factor for the properties of HEMT. 相似文献
83.
《Current Applied Physics》2015,15(10):1222-1225
Light-emitting diodes (LEDs) with a Mg-doped p-type Ga1−xInxN (0 ≤ x ≤ 0.07) spacer layer located between an undoped GaN spacer layer and the electron blocking layer are investigated. The LEDs are found to have comparable peak efficiency but less efficiency droop when the crystal quality of the p-type Ga1−xInxN spacer layer is well-controlled by lowering the growth temperature and by using a suitable In composition and Mg doping concentration. All LED samples with the p-type spacer layer show a smaller efficiency droop compared to a reference LED having an undoped GaN spacer. Among the sample sets investigated, an optical power enhancement of 12% at 111 A/cm2 is obtained when inserting a 5 nm-thick p-type Ga0.97In0.03N spacer layer. The results support that carrier transport is the key factor in the efficiency droop observed in GaN-based LEDs. 相似文献
84.
85.
Investigation of laterally single-diffused metal oxide semiconductor (LSMOS) field effect transistor
《Current Applied Physics》2015,15(10):1130-1133
We propose a distinct approach to implement a laterally single diffused metal-oxide-semiconductor (LSMOS) FET with only one impurity doped p-n junction. In the LSMOS, a single p-n junction is first created using lateral dopant diffusion. The channel is formed in the p region of the p-n junction and the n region acts as the drift region. Two distinct metals of different work function are used to form the “n+” source/drain regions and “p+” body contact using the charge plasma concept. We demonstrate that the LSMOS is similar in performance to a laterally double diffused metal-oxide-semiconductor (LDMOS) although it has only one impurity doped p-n junction. The LSMOS exhibits a breakdown voltage of ∼50.0 V, an average ON-resistance of 48.7 mΩ-mm2 and a peak transconductance of 53.6 μS/μm similar to that of a comparable LDMOS. 相似文献
86.
Mechanistic Study of the Role of Primary Amines in Precursor Conversions to Semiconductor Nanocrystals at Low Temperature
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Dr. Kui Yu Dr. Xiangyang Liu Queena Y. Chen Prof. Huaqing Yang Prof. Mingli Yang Xinqin Wang Prof. Xin Wang Dr. Hong Cao Dr. Dennis M. Whitfield Prof. Changwei Hu Dr. Ye Tao 《Angewandte Chemie (International ed. in English)》2014,53(27):6898-6904
Primary alkyl amines (RNH2) have been empirically used to engineer various colloidal semiconductor nanocrystals (NCs). Here, we present a general mechanism in which the amine acts as a hydrogen/proton donor in the precursor conversion to nanocrystals at low temperature, which was assisted by the presence of a secondary phosphine. Our findings introduce the strategy of using a secondary phosphine together with a primary amine as new routes to prepare high‐quality NCs at low reaction temperatures but with high particle yields and reproducibility and thus, potentially, low production costs. 相似文献
87.
Gerardo Algara‐Siller Dr. Nikolai Severin Samantha Y. Chong Dr. Torbjörn Björkman Dr. Robert G. Palgrave Andrea Laybourn Prof. Dr. Markus Antonietti Prof. Yaroslav Z. Khimyak Dr. Arkady V. Krasheninnikov Prof. Dr. Jürgen P. Rabe Prof. Dr. Ute Kaiser Prof. Andrew I. Cooper Prof. Dr. Arne Thomas Dr. Michael J. Bojdys 《Angewandte Chemie (International ed. in English)》2014,53(29)
88.
Dmitriy V. Steglenko Nikolay V. Tkachenko Alexander I. Boldyrev Ruslan M. Minyaev Vladimir I. Minkin 《Journal of computational chemistry》2020,41(15):1456-1463
The structure and properties of two-dimensional phosphoborane sheets were computationally investigated using Density Functional Theory calculations. The calculated phonon spectrum and band structure point to dynamic stability and allowed characterization of the predicted two-dimensional material as a direct-gap semiconductor with a band gap of ~1.5 eV. The calculation of the optical properties showed that the two-dimensional material has a relatively small absorptivity coefficient. The parameters of the mechanical properties characterize the two-dimensional phosphoborane as a relatively soft material, similar to the monolayer of MoS2. Assessment of thermal stability by the method of molecular dynamics indicates sufficient stability of the predicted material, which makes it possible to observe it experimentally. 相似文献
89.
Due to their special polar structure, amphiphilic molecules are simple to process, low in cost and excellent in material properties. Thus, they can be widely applied in the preparation of functional film materials and bionics related to cell membranes. Therefore, amphiphilic organic semiconductor materials are receiving increasing attention in research and industrial fields. The structure of organic amphiphilic semiconductor molecules usually consists of three functional parts: a hydrophilic group, a hydrophobic group, and a linking group between them. The adjustment of their correlation to achieve the target performance is particularly important and needs experimental discussion regarding synthetic methodologies. In this work, we focused on the engineering of a substituent alkyl-chain, and an amphiphilic functional molecule (benzo[b]benzo[4, 5] thieno[2, 3-d]thiophene, named CnPA-BTBT, n = 3–11) was proposed and synthesized. This molecule links the hydrophobic semiconductor backbone and hydrophilic polar group through alkyl chains of different lengths. Fundamental properties were investigated by nuclear magnetic resonance (NMR) and ultraviolet-visible spectroscopy (UV-Vis) to conform the structure and the band gap properties of the designed organic semiconductor. Thermodynamic features were investigated by thermogravimetric analysis (TGA) and corresponding differential thermal gravity (DTG), which indicate that the functional molecule CnPA-BTBT (n = 3–11) has a great stability in ambient conditions. Moreover, the results show that the binding ability of the amphiphilic molecule to water molecules was regulated by the odd-even alternating effect of the alkyl chain and the intramolecular coupling with BTBT. Furthermore, differential scanning calorimetry (DSC) and polarized optical microscopy (POM) were used to study the material properties in detail. As the length of the alkyl chain increased, the functional molecule CnPA-BTBT (n = 3–11) gradually changed from "hard" species with no thermodynamic changes to a transition one with a pair of thermodynamic peaks, and eventually to a "soft" one as a typical liquid crystal with clear observation of Maltese-cross spherulites. The cooling and freezing points were further studied, and the values and trends of their enthalpy and corresponding temperature fluctuated and alternated due to the volume effect, odd-even alternating effect, flexibility, and other functions of the alkyl chain. Three molecular models were proposed according to the thermodynamic study results, namely the brick-like model, transition model, and liquid crystal model. This work presents in-depth discussion on material structure and corresponding thermodynamic properties, and it is an experimental basis for the design, synthesis, optimization, and screening of target performance materials. 相似文献
90.
《中国化学快报》2020,31(12):3047-3054
As a class of metal-free two-dimensional (2D) semiconductor materials, polymeric carbon nitrides have attracted wide attention recently due to its facile regulation of the molecular and electronic structures, availability in abundance and high stability. According to the different ratios of C and N atoms in the framework, a series of CxNy materials have been successfully synthesized by virtue of various precursors, which further triggers extensive investigations of broad applications ranging from sustainable photocatalytic reactions and highly sensitive optoelectronic biosensing. In view of topological structures on their electronic structures and material properties, the as-reported CxNy could be generally classified into two main categories with three- or six-bond-extending frameworks. Owing to the effective n→π* transition in most CxNy materials, the relative energy level of the lone-pair electrons on N atoms is high, which thus endows the materials with the capability of visible light absorption. Meanwhile, the different repeating units, bridging groups and defect sites of these two kinds of CxNy allow them to effectively drive a diverse of promising applications that require specific electronic, interfacial and geometric properties. This review paper aims to summarize the recent progress in topological structure design and the relevant electronic band structures and striking properties of CxNy materials. In the final part, we also discuss the existing challenges of CxNy and outlook the prospect possibilities. 相似文献