NiS2 Co-catalyst decoration on CdLa2S4 nanocrystals for efficient photocatalytic hydrogen generation under visible light irradiation

NiS₂ nanoparticles as noble metal-free co-catalysts were deposited onto the CdLa₂S₄ nanocrystals through a hydrothermal process. The loading of NiS₂ co-catalyst resulted in remarkable enhancement for H₂ production over the CdLa₂S₄ photocatalyst under visible light irradiation. The optimal hybrid photocatalyst with 2 wt% NiS₂ loading exhibited a H₂ production rate of 2.5 mmol h⁻¹ g⁻¹, which was more than 3 times higher than that of the pristine CdLa₂S₄ photocatalyst. The promoted photocatalytic H₂ production by NiS₂-loading is attributed to the enhanced separation of photogenerated electrons and holes as well as the activation effect of NiS₂ for H₂ evolution.     

Investigation of thermal effects on the single-finger heterojunction bipolar transistors

We will first derive a physics-based, analytical single-finger heterojunction bipolar transistor (HBT) model which takes into account the thermal effect. Next, the model is used to calculate the three figures of merit of HBT, i.e., current gain, cut-off frequency and maximum frequency. Their variation against the collector current density under the influence of thermal effect is presented and the calculation results are discussed.     

UHV/CVD生长本征硅外延层的研究

在微波双极型晶体管中,收集区的厚度是影响其截止频率的一个重要因素。普通的常压外延难以生长出杂质浓度变化陡峭的薄外延层。文章利用自行研制的超高真空化学气相淀积(UHV/CVD)系统SGE500,在N型(掺As)重掺杂衬底上进行了薄本征硅外延层生长规律的研究;并采用扩展电阻(SPR)、原子力显微镜(AFM)、双晶衍射(DCXRD)等方法,对外延层的质量进行了评价。采用该外延材料制作的锗硅异质结双极型晶体管(SiGe HBT)器件击穿特性良好。     

Electrical and photoelectrical properties of P3HT/n-Si hybrid organic–inorganic heterojunction solar cells

A detail analysis of electrical and photoelectrical properties of hybrid organic–inorganic heterojunction solar cells poly(3-hexylthiophene) (P3HT)/n-Si, fabricated by spin-coating of the polymeric thin film onto oxide passivated Si(1 0 0) surface, was carried out within the temperature ranging from 283 to 333 K. The dominating current transport mechanisms were established to be the multistep tunnel-recombination and space charge limited current at forward bias and leakage current through the shunt resistance at reverse bias. A simple approach was developed and successfully applied for the correct analysis of the high frequency C–V characteristics of hybrid heterojunction solar cells. The P3HT/n-Si solar cell under investigation possessed the following photoelectric parameters: J_sc = 16.25 mA/cm², V_oc = 0.456 V, FF = 0.45, η = 3.32% at 100 mW/cm² AM 1.5 illumination. The light dependence of the current transport mechanisms through the P3HT/n-Si hybrid solar cells is presented quantitatively and discussed in detail.     

n型苝/p型无金属酞菁异质复合多层膜的紫外-可见吸收谱研究

利用真空蒸发技术生长了层厚为纳米数量级的n型导电系衍生物 (全氟取代酰亚胺 ) /p型导电无金属酞菁异质复合多层膜 ,并测试了样品的紫外 -可见吸收光谱。UV -Vis吸收谱实验结果表明 ,对应酞菁Q带吸收的主峰消失 ,次峰发生蓝移 ;全氟取代酰亚胺的吸收峰也发生蓝移 ,吸收带宽度扩展。结果表明 ,复合多层结构中与酞菁之间的电荷转移及纳米层厚导致的量子尺寸效应使分子中电子跃迁发生变化 ,导致吸收谱改变     

Reliability of III–V based heterojunction bipolar transistors

This paper reviews the reliability of III-V based heterojunction bipolar transistors (HBTs). These devices have many potential advantages over other solid-state microwave devices. However, because of the tradeoff between performance and reliability, they are not being used to any great extent in power microwave applications. In the type of III-V HBT device most fully developed, the AlGaAs/GaAs HBT, leakage currents play a major role in the dominant mode of degradation. Because low-frequency noise is related to these leakage currents it has been used extensively in the analysis of the performance and reliability limitations of these devices. The reliability of other types of III-V HBT devices, such as InGaP/GaAs and InP based devices, is also discussed.     

Si/SiGe/Si HBT频率特性的解析模型与模拟

用解析的方法模拟了T＝300K和77K时，fT和fmax与集电极电流密度Jc的关系，在大电流下考虑了异质结势垒效应的影响。模拟结果和用数值方法以及实验所得到的结果一致。同时，还建立了与之相应的Si／SiGeeb异质结和SiGe／Sibc异质结电容模型。     

Formation of CuSbS2 and CuSbSe2 thin films via chalcogenisation of Sb-Cu metal precursors

Due to the availability and low cost of the elements, the ternary Cu-Sb-S and Cu-Sb-Se semiconductor systems are being studied as sustainable alternative absorber materials to replace CuIn(Ga)(S,Se)₂ in thin film photovoltaic applications.Simple evaporation of the metal precursors followed by annealing in a chalcogen environment has been employed in order to test the feasibility of converting stacked metallic layers into the desired compounds. Other samples have been produced from aqueous solutions by electrochemical methods that may be suitable for scale-up.It was found that the minimum temperature required for the complete conversion of the precursors into the ternary chalcogen is 350 °C, while binary phase separation occurs at lower temperatures.The new materials have been characterised by structural, electrical and photoelectrochemical techniques in order to establish their potential as absorber layer materials for photovoltaic applications. The photoactive films consisting of CuSbS₂ and CuSbSe₂ exhibit band-gap energies of ~ 1.5 eV and ~ 1.2 eV respectively, fulfilling the Shockley-Queisser requirements for the efficient harvesting of the solar spectrum.     

Preparation of (n) a-Si: H/(p) c-Si heterojunction solar cells

Heterojunction solar cells have been manufactured by depositing n-type a-Si: H on p-type 1–2Ω cm CZ single crystalline silicon substrates. Although our cell structure is very simple - neither a BSF nor a surface texturing is used - a conversion efficiency of 13.1% has been achieved on an area of 1 cm². In this paper the technology is described and the dependence of the solar cell parameters on the properties of the n-type a-Si: H layer is discussed. It is shown that this cell type exhibits no degradation under light exposure.