InAs／InP_（0．7）Sb_（0．3）热电子晶体管的f_T及f_（max）

用电荷控制及热电子弹道运动模型计算ＩｎＡｓ／ＩｎＰ０．７Ｓｂ０．３热电子晶体管的截止频率ｆＴ及最高振荡频率ｆｍａｘ。结果表明，ｆＴ、ｆｍａｘ分别达到２８０ＧＨｚ及６００ＧＨｚ。并指出，通过生长ＧａＳｂ中间层，ＩｎＡｓ／ＩｎＰ０．７Ｓｂ０．３ＨＥＴ可在ＧａＡｓ衬底上实现单片集成。     

Tuning of electronic states in self-assembled InAs quantum dots using an ion implantation technique

We report the tunability of up to 150 meV of the ground state transition of self-assembled InAs quantum dots (QDs) using Mn ion implantation and subsequent annealing. Because of the exciton localization in the quantum dots, the photoluminescence efficiency (T=12K) of the quantum dot transition remains at 80% of its original value after implantation with a Mn dose of 1×10¹³ cm⁻²ions. Strong luminescence still remains at room temperature. At a high implantation dose (1×10¹⁵ cm⁻²) and rapid thermal annealing (700°C for 60s) about 25% of the QD luminescence intensity is recovered at T=12K.     

CdSe/ZnS量子点的合成及表征

本文于水溶液中采用3-巯基丙酸作为稳定剂,成功合成了CdSe/ZnS核壳型量子点。透射电子显微镜观察表明,所合成的量子点尺寸均一,形貌近似球形,粒子大小在5 nm以下。紫外吸收光谱和荧光光谱分析表明,所合成的CdSe/ZnS核壳型量子点较之CdSe量子点更具良好光学特性。     

InAs基范德华异质结界面电荷转移特性第一性原理计算的研究进展

由低维InAs材料和其他二维层状材料堆叠而成的垂直范德华异质结构在纳米电子、光电子和量子信息等新兴领域中应用广泛。探索跨结界面的电荷转移机制对于全面理解该类器件的非凡特性至关重要。第一性原理计算在揭示界面电荷转移特性与各种能量稳定型InAs基范德华异质结的电、光、磁等原理物理特性和器件性能变化之间的内在关系方面发挥着不可比拟的作用。文中梳理、总结和探讨了近年来InAs基范德华异质结间界面电荷转移特性的理论研究工作与潜在的功能应用,提出在理论方法和计算精度方面大力发展第一性原理计算的几个途径,为更好地开展InAs基范德华异质结的基础科学研究和应用器件设计提供可借鉴的量化研究基础。     

Determination of lysozyme at the nanogram level in chicken egg white using Resonance Rayleigh-scattering method with Cd-doped ZnSe quantum dots as probe

A new method for the determination of lysozyme with high sensitivity based on Resonance Rayleigh scattering (RRS) by using Cd doped ZnSe quantum dots (QDs) as a probe was proposed in this experiment. Cd doped ZnSe QDs capped with glutathione were prepared in the water phase. Further, the RRS spectrum, transmission electron microscope, and absorption spectrum of the QDs-lysozyme system have been characterized. In addition, the effects of several factors on scattering intensities were investigated, including pH value of solution, amount of QDs, mixing sequence of each reagent and the coexisting substances. Moreover, the possible mechanism for the RRS enhancement of Cd doped ZnSe QDs-lysozyme system was preliminary discussed. The RRS method for the determination of lysozyme has good sensitivity with the detection limits 6.5 × 10⁻¹⁰ g mL⁻¹. The contents of lysozyme were determined with recoveries of 97.1-101.6% and relativity standard deviation of 2.5-3.1%, respectively. It proved that the method established in our study is very sensitive, rapid, convenient and tolerant for the determination of lysozyme in synthetically and chicken egg white.     

1.3 μm InAs quantum dot resonant cavity light emitting diodes

Resonant cavity light emitting diodes (RCLEDs) containing nine sheets of self-organized InAs quantum dot (QD) active layers and operating at around 1.3 μm are demonstrated. The structure was grown directly on GaAs substrates, which includes selectively oxidized AlO_x current apertures and intracavity metal contacts. It was found that the average operating resistance is 60 Ω, while the average turn-on voltages is 1.6 V. It was also found that temperature coefficient of these RCLEDs was about 0.11 nm/°C.     

Study of thiol capped CdSe quantum dots using SeO2 precursor for selenium source

CdSe quantum dots in aqueous medium using thioglycollic acid as capping agent have been synthesized. The reaction was carried out in an open atmosphere at pH of 12 and refluxed at 100 °C for 8 h. Selenium dioxide which is less expensive and less toxic has been used as a precursor for selenium source by replacing Se powder and sodium selenite. For characterization QD solutions was taken at different time intervals ranging from 15 min to 6 h. UV–Vis spectroscopy shows that there is a strong blue shift in the prepared quantum dots due to quantum confinement effect. Band gap calculated at different time intervals lies between 2.34 and 2.73 eV which is more than the bulk band gap 1.74 eV and with the increase in size of the QDs, bandgap also decreases. Photoluminescence study was carried out at excitation wavelength of 350 nm and results shows that with increase in time the peak position shift toward higher wavelength. FTIR spectroscopy shows peaks of thioglycollic acid. SEM micrographs of the prepared quantum dots show zero dimensional spherical particles in nm range. For electrical conductivity dc conductivity measurement has been done which shows that with increase of temperature conductivity increases, it confirms the semiconducting nature of the quantum dot. Conduction mechanism found to be mainly due to localized states.     

Improving optical properties of CdTe quantum dots by a new multidentae biopolymer based on salep

In this work, we have successfully modified aqueous CdTe quantum dots (QDs) by a biopolymer based on poly (2-hydroxyethyl methacrylate) grafted onto salep via a facile method at room temperature. The obtained QDs were characterized using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TG), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The size of the prepared QDs was estimated around 1.5 nm by TEM and XRD. Optical properties of modified QDs were monitored by absorption and fluorescence spectrophotometers. It was found that the fluorescence intensity of CdTe QDs was enhanced after coating by biopolymer. Finally, the fluorescence intensity of CdTe QDs was investigated at different temperatures and times.