高速光探测器封装的优化设计

提出了一种高速光探测器封装优化设计的新方法。首先用矢量网络分析仪对封装寄生参量和探测器芯片进行准确测量,研究了探测芯片的本征参量与封装寄生参量之间的谐振现象,然后合理利用这种谐振效应对芯片的频率响应特性进行有效补偿。理论分析和实验结果都证明优化封装后器件的频率响应带宽超过了芯片的响应带宽。该方法不需要另加其它元件．而仅仅利用光电器件封装过程中必不可少的金丝所带来的寄生电感,就达到了改善器件频率响应特性的目的。     

半导体激光器同轴封装的高频影响:分析与实验

存高频调制下,封装对半导体激光器的影响非常显著。通过分析封装前后激光器散射参量之间的火系,推导出可用于分析半导体激光器封装高频影响的两种方法：预测法和评价法,从而提供了分析激光器封装的另外两种等价方法。实验中,对同轴（TO）封装的高频特性进行了测试和分析,分析结果与传统比较法的测试结果吻合表明新方法有效。实验表明在10．2GHz以内同轴封装不会降低半导体激光器的频响带宽,即同轴封装的带宽可达10GHz,且发现同轴封装巾电感和电容元件之间的谐振效应对器件的顿响具有补偿作用。两方法可为筛选光电子器件封装提供依据,并为优化封装的设计提供参考。     

光通信用雪崩光电二极管(APD)频率响应特性研究

吸收层、电荷层和倍增层分离结构雪崩光电二极管(SACM-APD),包括InP/InGaAs、InAlAs/InGaAs和Si/Ge APD是光通信领域近年来研究的热点. 本文基于电路模型,系统比较了不同外延层厚度、不同材料以及不同结构APD的频率响应特性,重点探讨Si/Ge APD吸收层厚度、光敏面大小、寄生参数等各项参数对带宽的影响,仿真结果与实际器件实验数据相符合. 本文的研究成果对SACM-APD的优化设计具有指导意义. 关键词： SACM-APD 电路模型 频率响应     

高探测效率CMOS单光子雪崩二极管器件

基于标准0.35μm CMOS工艺设计了一种单光子雪崩二极管器件.采用p+n阱型二极管结构,同时引进保护环与深n阱结构以提高单光子雪崩二极管性能;研究了扩散n阱保护环宽度对雪崩击穿特性的影响;对器件的电场分布、击穿特性、光子探测效率、频率响应等特性进行了分析.仿真结果表明:所设计的单光子雪崩二极管器件结构直径为10μm,扩散n阱保护环宽度为1μm时,雪崩击穿电压为13.2 V,3 dB带宽可达1.6 GHz;过偏压为1 V、2 V时最大探测效率分别高达52%和55%;在波长500~800 nm之间器件响应度较好,波长为680 nm时单位响应度峰值高达0.45 A/W.     

半导体量子器件物理讲座第七讲半导体异质结光电探测器

光电探测器是一类用于接收光波并转变为电信号的专门器件，文章描述了PIN光电二极`管雪崩光电二极管、MSM（金属－半导体－金属）光电二极管的器件结构和工作原理，并对它们的响应度、噪声、带宽等特性进行了讨论，这类器件已在光通信、光信息处理等许多系统中得到广泛的应用。     

带有锥度结构的同轴开槽布拉格反射器研究

本文提出在Kα波段圆柱过模结构绕射辐射器件(RDG)中引入一种带有锥度结构的同轴内开槽布拉格反射器.采用复功率守恒技术(CCPT)对该反射器的频率响应特性进行分析.研究了相位匹配段长度,波纹槽深及锥度对反射器频率响应特性的影响,分析了波纹初始相位对反射器选模特性的影响,发现该反射器具有良好的模式选择特性.本文的研究工作为同轴Bragg反射器结构的研究提供了重要的理论分析手段. 关键词： 同轴Bragg反射器 频率响应特性 复功率守恒 绕射辐射振荡器     

PIN光电探测器的建模与仿真分析

为了优化PIN光电探测器响应特性,首先依据载流子速率方程,并考虑芯片寄生参量和封装寄生参量,建立光电探测器的等效电路模型。然后仿真分析了反偏电压、I区宽度、光敏面、芯片寄生电阻和电容、封装寄生电阻、电容和电感对光电探测器脉冲响应特性和频率响应特性的影响。结果表明:通过增大反偏电压,减小光敏面和寄生参量(芯片寄生电容和电阻,封装寄生电容和电阻),选取合适的I区宽度,利用引线电感的谐振效应现象,可以抑制脉冲响应波形畸变,提高频率响应带宽。     

基于扣除法的电吸收调制器本征特性分析方法

基于电吸收调制器的工作原理和等效电路模型对调制器的高频响应特性进行分析,提出了一种采用频率响应扣除法提取有源区本征响应的仿真新方法.该方法能简单地去掉封装网络、夹具及光探测仪器等带来的影响,用该方法得到了待测lnGaAs/InAIAs材料电吸收调制器准确的的高频本征响应特性.     

In_(0.53)Ga_(0.47)As/InP雪崩光电二极管响应及电学特性

通过分子束外延生长和开管式Zn扩散方法,制备了低暗电流、宽响应范围的In_(0.53)Ga_(0.47)As/InP雪崩光电二极管.在0.95倍雪崩击穿电压下,器件暗电流小于10nA;-5V偏压下电容密度低至1.43×10~(-8) F/cm~2.在1 310nm红外光照及30V反向偏置电压下,雪崩光电二极管器件的响应范围为50nW~20mW,响应度达到1.13A/W.得到了电荷层掺杂浓度、倍增区厚度结构参数与击穿电压和贯穿电压的关系:随着电荷层电荷密度的增加,器件贯穿电压线性增加,而击穿电压线性降低;电荷层电荷面密度为4.8×10~(12)cm~(-2)时,随着倍增层厚度的增加,贯穿电压线性增加,击穿电压增加.通过对器件结构优化,雪崩光电二极管探测器实现25V的贯穿电压和57V的击穿电压,且具有低暗电流和宽响应范围等特性.     

InGaAs/Si键合界面a-Si键合层厚度对InGaAs/Si雪崩光电二极管性能的影响

为从根本上阻断InGaAs/Si之间的失配晶格,获得低噪声的InGaAs/Si雪崩光电二极管,理论上在InGaAs/Si键合界面插入超薄a-Si键合层,彻底隔断键合界面异质晶格,同时保证InGaAs吸收层和Si倍增层超高的晶体质量和良好的电学传输.模拟了a-Si键合层厚度对InGaAs/Si雪崩光电二极管性能影响.由于...     

Potential frequency bandwidth estimation of TO packaging techniques for photodiode modules

Scattering parameters of photodiode chip, TO header and TO packaged module are measured, and the effects of TO packaging network on the high-frequency response of photodiode are investigated. Based on the analysis, the potential bandwidth of TO packaging techniques is estimated from the scattering parameters of the TO packaging network. Another method for estimating the potential bandwidth from the equivalent circuit for the TO packaged photodiode model is also presented. The results obtained using both methods show that the TO packaging techniques used in the experiments can potentially achieve a frequency bandwidth of 22 GHz.     

Frequency Bandwidth Estimation of TO Packaging Techniques for Laser Modules

Two simple methods for estimating the potential modulation bandwidth of TO packaging technique are presented. The first method is based upon the comparison of the measured frequency responses of the laser diodes and the TO laser modules, and the second is from the equivalent circuit for the test fixture, the TO header, the submount and the bonding wire. It is shown that the TO packaging techniques used in the experiments can potentially achieve a frequency bandwidth of over 10.5 GHz, and the two proposed methods give similar results.     

Modelling of a DNA packaging motor

During the assembly of many viruses, a powerful molecular motor packages the genome into a preassembled capsid. The Bacillus subtilis phage φ 29 is an excellent model system to investigate the DNA packaging mechanism because of its highly efficient \textitin vitro DNA packaging activity and the development of a single-molecule packaging assay. Here we make use of structural and biochemical experimental data to build a physical model of DNA packaging by the φ 29 DNA packaging motor. Based on the model, various dynamic behaviours such as the packaging rate, pause frequency and slip frequency under different ATP concentrations, ADP concentrations, external loads as well as capsid fillings are studied by using Monte Carlo simulation. Good agreement is obtained between the simulated and available experimental results. Moreover, we make testable predictions that should guide future experiments related to motor function.     

不同封装方式对肖特基二极管高频性能的影响

肖特基二极管是太赫兹接收机的关键器件,通过在高频下对不同封装形式的肖特基二极管进行建模仿真,研究不同封装方式对肖特基二极管性能的影响。首先通过建立肖特基二极管的仿真模型,在高频结构仿真软件HFSS中对肖特基二极管在0~120GHz频段进行仿真,得到该肖特基二极管的S参数,并对S参数仿真结果和实测结果进行对比,证明了该二极管模型的准确性。然后分别建立肖特基二极管的普通封装模型和肖特基二极管的倒装芯片(flip-chip)封装模型,并对这两种封装模型进行仿真,得到其在两种不同封装结构下的S参数,进而对两种不同封装方式的S参数的-3dB带宽以及相位一致性进行对比分析。最终,对应用于太赫兹波段的肖特基二极管由于封装不同而带来的带宽以及相位的区别及其成因进行分析,论证了flipchip封装更适合应用于太赫兹波段的肖特基二极管,与普通封装相比,该封装在高频下对肖特基二极管的电性能有比较大的改进。     

Polar phonon mixing in magnetoelectric EuTiO3

Infrared reflectivity spectra of antiferromagnetic incipient ferroelectric EuTiO₃ were investigated up to 600 K. Three polar phonons typical for the cubic perovskite Pm[`3]mPm\bar {3}m structure were observed. Analysis of phonon plasma frequencies showed that the lowest-energy TO1 phonon corresponds predominantly to the Slater mode describing vibration of Ti cations against the oxygen octahedra and the TO2 phonon expresses vibrations of the Eu cation against the TiO₆ octahedra. The highest frequency TO4 phonon represents O-octahedra bending. Incipient ferroelectric behavior of the permittivity is caused by pronounced softening of the TO1 phonon, which is coupled to the TO2 mode. Although the Eu cations are not involved in the TO1 mode, the spin ordering of the 4f electrons at Eu cations has influence on the frequency of the TO1 mode due to Eu-O-Eu super-exchange interaction. This is probably responsible for the 7% change of the permittivity induced by the magnetic field in the antiferromagnetic phase, as reported by Katsufuji and Takagi [Phys. Rev. B 64, 054415 (2001)].     

Effects of Au coating on thermal stresses in stainless-to-Kovar packages

A finite-element method (FEM) analysis has been carried out on the thermally-induced stresses generated when stainless steel covers are laser-welded to Au-coated Kovar TO headers during the packaging of semiconductor lasers. In particular, the effect of varying the Au coating thickness of these stresses was investigated. Maximum stresses were found to be reduced as the Au thickness increased. This effect is attributed to the reduction in thermal gradient in the weld region provided by the increased thermal conduction of thicker Au. The result suggests that adequate Au coating thickness is important for ensuring good reliability of opto-electronic packages having laser-welded caps. This revised version was published online in June 2006 with corrections to the Cover Date.     

Raman spectra of chainlike organopolysilane

Chainlike methyl-propyl-polysilane, which was stable even in air, has been synthesized to investigate the vibrational properties of long-chained-silicon skeletons. The vibrational frequencies for the LO and TO like modes, in which the silicon skeletons vibrate along and vertically, respectively, to the chain-direction, are definitely split due to the reduction in the crystallographic symmetry. The frequency for the LO like mode is hardly affected by the side chains attached to the back bones for the tetrahedrally bonded silicon skeletons. On the contrary, the frequency is greatly affected by the side chains for the TO like mode, which is due to the mass effect. In the case of the heavy side chains, the frequency for Si-(side chains) anti-symmetry like stretching vibrations becomes lower, and comparable to that for Si—Si vibrations.     

Incident-angle dependence of the longitudinal optic mode and the Doppler effect in silica glass

The infrared reflection spectra of silica glass were monitored at different incident angles of the wave. The density of states (DOS) and frequency ω_LO of the longitudinal optic (LO) mode were found to be the functions of the incident angle. The DOS of the LO mode increases with increasing incident angle as a whole. However, two regions can be divided in which one is below ∼30° and the other is above 30°. The frequency ω_LO of the LO mode increases linearly with incident angle. The earlier proposed relationship between the shifted frequency produced by the Doppler effect and the source frequency of the main transverse optic (TO) mode was investigated by studying the infrared spectra of the annealed glass capillaries. The shifted frequency was found to be linearly proportional to the source frequency of the TO mode, as depicted by the Doppler effect.     

Structural and dielectric properties of Er substituted sol-gel fabricated PbTiO3 thin films

Er substituted lead titanate thin films were processed via chemical solution deposition. Their structural properties were investigated by means of atomic force microscopy, X-ray diffractometry and micro-Raman spectroscopy. The Curie temperature, T_C, was obtained from dielectric measurements. The results show that the grain size, tetragonality factor, c/a, E(1TO) transverse optical phonon frequency and the ferroelectric-to-paraelectric phase transition are affected by Er doping. Particularly the lattice tetragonality and Curie temperature of Er substituted films are found to be substantially lower in comparison to undoped specimen. In contrast, the E(1TO) phonon frequency is only slightly reduced by Er doping. The Results obtained for pure and Er substituted specimens are discussed in terms of combined effects of grain size, stress development and doping on the structural characteristics. PACS 68.55.-a; 77.80.Bh; 78.30.Hv