Dual approach for bipolar transistor thermal impedance determination

This paper presents a dual approach for a coherent determination and validation of heterostructure bipolar transistor (HBT) thermal impedance. This study relies both on an experimental characterization method and a 3D finite element simulation approach. One section reminds briefly the experimental approach. Another describes the 3D device modeling used for the physics-based thermal simulation. Thereafter, details on the reduction method used for the numerical computation of the thermal impedance are given. As complement to pure thermal simulation, an electrothermal distributed model is proposed and gives an interpretation of the distributed effects in multi-finger devices.     

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.     

与InP晶格相匹配的Ga_xIn_(1-x)P_yAs_(1-y)半导体的光学常数计算

采用半经验的紧束缚方法计算了与InP晶格相匹配的Ga_xIn_(1-x)P_yAs_(1-y)半导体的电子联合状态密度及介电常数虚部,并根据Kramers-Kronig关系式求得了光透明区的折射率常数.     

Near-infrared response photovoltaic device based on novel narrow band gap small molecule and PCBM fabricated by solution processing

In this paper, we report on synthesis of a novel diphenylaminofluorenyl-capped thiadiazoloquinoxaline (6,7-dimethyl-4,9-di{5-[9,9-bis(octyl)-7-diphenylaminofluorene-2-yl]-4-hexylthien-2-yl}[1,2,5]-thiadiazolo[3,4-g]quinoxaline (DPAFL-TDOX-DPAFL which is further abbreviated to TDOX), Scheme 1) and its use as donor material for the realization of efficient bulk-heterojunction organic solar cell by spin coating from blend with PCBM as acceptor. TDOX showed very good solution processibility and film uniformity up to weight ratio TDOX:PCBM=1:4. Spectral response was extended to near-infrared region (at around 1000 nm) with energy conversion efficiency (ECE) 0.75% and short-curcuit current density 1.95 mA/cm².