High performance oscillator with 2-mW output power at 300 GHz

Material structures and device structures of a 100-GHz InP based transferred-electron device are designed in this paper. In order to successfully fabricate the Gunn devices operating at 100 GHz, the InP substrate was entirely removed by mechanical thinning and wet etching. The Gunn device was connected to a tripler link and a high RF(radio frequency)output with power of 2 mW working at 300 GHz was obtained, which is high enough for applications in current military electronic systems.     

激光在PERC晶硅电池中背面点接触电极制备中的应用

在经过Al2O3全钝化发射极钝化局部背接触(PERC)结构电池的背面实现良好的接触电极一直是制约着PERC高效电池向产业化推广的重要因素之一。本文采用532 nm激光烧蚀背面钝化介质层方法和传统的光刻工艺来实现背面电极的局部接触,并对两种方法进行详细的比较与分析。对激光烧蚀和激光烧结两种不同的局部接触电极制备方式进行了对比,发现激光烧蚀是更为适宜的工艺方式。相较于激光烧结,以激光烧蚀方式制备的电池的串联面接触电阻从10.7Ω.cm2降到1.24Ω.cm2,效率从4.2%提高到10.7%。     

A comparison of silicon oxide and nitride as host matrices on the photoluminescence from Er+ ions

This paper compares the properties of silicon oxide and nitride as host matrices for Er ions.Erbium-doped silicon nitride films were deposited by a plasma-enhanced chemical-vapour deposition system.After deposition,the films were implanted with Er3+ at different doses.Er-doped thermal grown silicon oxide films were prepared at the same time as references.Photoluminescence features of Er3+ were inspected systematically.It is found that silicon nitride films are suitable for high concentration doping and the thermal quenching effect is not severe.However,a very high annealing temperature up to 1200° C is needed to optically activate Er3+,which may be the main obstacle to impede the application of Er-doped silicon nitride.     

光管理在晶体硅电池中的应用

光管理是提高晶体硅太阳能电池光吸收和短路电流（Jsc）进而提高转换效率的重要因素之一。本文回顾了最常见的光管理方式,包括表面抗反射、散射以及陷光等。为了降低晶体硅电池的表面反射损失,开发了多种表面抗反射结构。例如,仿生蛾眼结构利用渐变折射率实现了宽光谱低反射率,其表面反射率可达1％以下。随着晶体硅电池衬底减薄,光管理要求更加严格,除了在更宽波长范围内达到超低反射率外,还需要在更高的入射角范围内实现低反射率。此外,利用前表面散射以及背表面陷光结构提高红外光的吸收光程对于晶体硅电池特别是薄衬底晶体硅电池的有效光吸收具有重要意义。     

Heterogeneous integration of InP HEMTs on quartz wafer using BCB bonding technology

Heterogeneous integrated InP high electron mobility transistors(HEMTs)on quartz wafers are fabricated successfully by using a reverse-grown InP epitaxial structure and benzocyclobutene(BCB)bonding technology.The channel of the new device is In_0.7Ga_0.3As,and the gate length is 100 nm.A maximum extrinsic transconductance gm,max of 855.5 mS/mm and a maximum drain current of 536.5 mA/mm are obtained.The current gain cutoff frequency is as high as 262 GHz and the maximum oscillation frequency reaches 288 GHz.In addition,a small signal equivalent circuit model of heterogeneous integration of InP HEMTs on quartz wafer is built to characterize device performance.     

Impact of symmetric gate-recess length on the DC and RF characteristics of InP HEMTs

We fabricated a set of symmetric gate-recess devices with gate length of 70 nm.We kept the source-to-drain spacing(L_SD)unchanged,and obtained a group of devices with gate-recess length(L_recess)from 0.4μm to 0.8μm through process improvement.In order to suppress the influence of the kink effect,we have done SiN_X passivation treatment.The maximum saturation current density(ID_max)and maximum transconductance(g_m,max)increase as L_recess decreases to 0.4μm.At this time,the device shows ID_max=749.6 mA/mm at V_GS=0.2 V,V_DS=1.5 V,and g_m,max=1111 mS/mm at V_GS=?0.35 V,V_DS=1.5 V.Meanwhile,as L_recess increases,it causes parasitic capacitance C_gd and g_d to decrease,making f_max drastically increases.When L_recess=0.8μm,the device shows f_T=188 GHz and f_max=1112 GHz.     

Optical matching layer structures in evanescent coupling photodiodes at a wavelength of 1.55μm： physics,design and simulation

We have studied the optical matching layers (OMLs) and external quantum efficiency in the evanescent coupling photodiodes (ECPDs) integrating a diluted waveguide as a fibre-to-waveguide coupler, by using the semi-vectorial beam propagation method (BPM). The physical basis of OML has been identified, thereby a general designing rule of OML is developed in such a kind of photodiode. In addition, the external quantum efficiency and the polarization sensitivity versus the absorption and coupling length are analysed. With an optical matching layer, the absorption medium with a length of 30μm could absorb 90% of the incident light at 1.55μm wavelength, thus the total absorption increases more than 7 times over that of the photodiode without any optical matching layer.     

Extrinsic equivalent circuit modeling of InP HEMTs based on full-wave electromagnetic simulation

With the widespread utilization of indium-phosphide-based high-electron-mobility transistors (InP HEMTs) in the millimeter-wave (mmW) band, the distributed and high-frequency parasitic coupling behavior of the device is particularly prominent. We present an InP HEMT extrinsic parasitic equivalent circuit, in which the conductance between the device electrodes and a new gate-drain mutual inductance term L_mgd are taken into account for the high-frequency magnetic field coupling between device electrodes. Based on the suggested parasitic equivalent circuit, through HFSS and advanced design system (ADS) co-simulation, the equivalent circuit parameters are directly extracted in the multi-step system. The HFSS simulation prediction, measurement data, and modeled frequency response are compared with each other to verify the feasibility of the extraction method and the accuracy of the equivalent circuit. The proposed model demonstrates the distributed and radio-frequency behavior of the device and solves the problem that the equivalent circuit parameters of the conventional InP HEMTs device are limited by the device model and inaccurate at high frequencies when being extracted.     

梯度掺杂对n型异质结太阳能电池性能的影响

通过仿真软件AFORS-HET对a-Si:H(p)/i-a-Si:H/c-Si(n)异质结太阳能电池的光伏特性进行分析及优化,主要对比了a-Si:H(p)层的均匀掺杂和表面掺杂浓度D₁=1×10²⁰ cm^-3>界面掺杂浓度D₂=4×10¹⁹ cm^-3的梯度掺杂情况时的光伏特性,实现了在梯度掺杂时22.32%的光电转换效率。与均匀梯度掺杂相比,发射层的梯度掺杂除了引入一个附加电场,还优化了能带结构、光谱响应、表面复合速率。结果表明,梯度掺杂可以有效地改善电池的光电转换性能。     

用PAA模板法实现硅基纳米孔阵列结构

用二次阳极氧化方法制备出分立、双向贯通并且超薄（500—1000 nm）的多孔阳极氧化铝膜,贴合到硅片上进行干法刻蚀,实现图形转移,得到了硅基纳米孔阵列结构,并对工艺中影响图形转移质量的因素进行了探索.扫描电镜（SEM）测试结果表明该途径得到的纳米结构孔形态均匀且大面积有序,孔深度可达到125 nm.对该样品进行热氧化处理后进行光致发光（PL）测试,结果表明其光致发光机理是基于通常较微弱的TO声子辅助的硅带边发光,并实现了显著发光增强,对这种增强效果的物理机理进行了理论分析.该结构具有的独特光学特性为利用 关键词： 多孔阳极氧化铝模板 硅基纳米孔阵列结构 图形转移