Thermal stability improvement of a multiple finger power SiGe heterojunction bipolar transistor under different power dissipations using non-uniform finger spacing

A method of non-uniform finger spacing is proposed to enhance thermal stability of a multiple finger power SiGe heterojunction bipolar transistor under different power dissipations. Temperature distribution on the emitter fingers of a multi-finger SiGe heterojunction bipolar transistor is studied using a numerical electro-thermal model. The results show that the SiGe heterojunction bipolar transistor with non-uniform finger spacing has a small temperature difference between fingers compared with a traditional uniform finger spacing heterojunction bipolar transistor at the same power dissipation. What is most important is that the ability to improve temperature non-uniformity is not weakened as power dissipation increases. So the method of non-uniform finger spacing is very effective in enhancing the thermal stability and the power handing capability of power device. Experimental results verify our conclusions.     

不同偏置影响锗硅异质结双极晶体管单粒子效应的三维数值仿真研究

针对国产锗硅异质结双极晶体管(SiGe HBT),采用半导体器件三维计算机模拟工具,建立单粒子效应三维损伤模型,研究不同偏置状态对SiGe HBT单粒子效应的影响.分析比较不同偏置下重离子入射器件后,各端口电流瞬变峰值和电荷收集量随时间的变化关系,获得SiGe HBT单粒子效应与偏置的响应关系.结果表明:不同端口对单粒子效应响应的最劣偏置不同,同一端口电荷收集量和瞬变电流峰值的最劣偏置也有所差异.载流子输运方式变化和外加电场影响是造成这种现象的主要原因.     

重离子导致的锗硅异质结双极晶体管单粒子效应电荷收集三维数值模拟

针对国产锗硅异质结双极晶体管(SiGe HBTs), 采用半导体器件模拟工具, 建立SiGe HBT单粒子效应三维损伤模型, 研究影响SiGe HBT单粒子效应电荷收集的关键因素. 分析比较重离子在不同位置入射器件时, 各电极的电流变化和感生电荷收集情况, 确定SiGe HBT电荷收集的敏感区域. 结果表明, 集电极/衬底结内及附近区域为集电极和衬底收集电荷的敏感区域, 浅槽隔离内的区域为基极收集电荷的敏感区域, 发射极收集的电荷可以忽略. 此项工作的开展为下一步采用设计加固的方法提高器件的抗辐射性能打下了良好的基础. 关键词： 锗硅异质结双极晶体管 单粒子效应 电荷收集 三维数值仿真     

不同剂量率下锗硅异质结双极晶体管电离损伤效应研究

对于相同制作工艺的NPN锗硅异质结双极晶体管(SiGe HBT), 在不同辐照剂量率下进行⁶⁰Co γ射线的辐照效应与退火特性的研究. 测量结果表明, 两种辐照剂量率下, 随着辐照总剂量增加, 晶体管基极电流增大, 共发射极电流放大倍数降低, 且器件的辐照损伤、性能退化与辐照剂量率相关, 低剂量率下辐照损伤较高剂量率严重. 在经过与低剂量率辐照等时的退火后, 高剂量率下的辐照损伤仍较低剂量率下的损伤低, 即待测SiGeHBT具有明显的低剂量率损伤增强效应(ELDRS). 本文对相关的物理机理进行了探讨分析. 关键词： 锗硅异质结双极晶体管 低剂量率辐照损伤增强 辐照效应     

Effect of Heavily Doped Boron on Bandgap Narrowing of Strained SiGe Layers

Taking into account the compensation effect of B to Ge in strained SiGe layers for the first time, the effect of heavily doped boron on the bandgap narrowing of strained SiGe layers is calculated, and the classical JainRoulston （J-R） model is modified. The results show that our modified J-R model well fits the experimental values. Based on the modified J-R model, the real bandgap narrowing distribution between the conduction and valence bands is further calculated, which has great influence on modelling the electrical characteristics of SiGe heterojunction bipolar transistors.     

Improved mobility of AIGaN channel heterojunction material using an AIGaN/GaN composite buffer layer

The quality of an A1GaN channel heterojunction on a sapphire substrate is massively improved by using an A1- GaN/GaN composite buffer layer. We demonstrate an A10.4Gao.6N/AI0.18Ga0.82N heterojunction with a state-of-the-art mobility of 815 cm2/（V.s） and a sheet resistance of 890Ω/口 under room temperature. The crystalline quality and the electrical properties of the A1GaN heterojunction material are analyzed by atomic force microscopy, high-resolution X-ray diffraction, and van der Pauw Hall and capacitance-voltage （C-V） measurements. The results indicate that the improved electrical properties should derive from the reduced surface roughness and low dislocation density.     

Effect of film thickness manganite-based on interfacial barrier of heterojunctions

Interracial barrier is a key factor that determines the performances of heterojunctions. In this work, we study the effect of manganite film thickness on the effective interracial barrier for La0.67Sr0.33MnO3/Nb：SrTiO3 junctions, The barrier is extracted from the forward current-voltage characteristics. Our results demonstrate that the barrier decreases gradually from -0.85 eV to -0.60 eV when the film thickness decreases from 150 nm to 2 nm. The overall value of the barrier is only about 50% of the corresponding one determined from the photovoltaic effect.     

新型宽温区高热稳定性微波功率SiGe 异质结双极晶体管

宽温区大电流下的热不稳定性严重制约着功率SiGe 异质结双极晶体管 (HBT) 在射频和微波电路中的应用.为改善器件的热不稳定性, 本文利用SILVACO TCAD建立的多指功率SiGe HBT模型, 分析了器件纵向结构中基区Ge组分分布对微波功率SiGe HBT电学特性和热学特性的影响. 研究表明, 对于基区Ge组分为阶梯分布的HBT, 由于Ge组分缓变引入了少子加速电场, 使它与均匀基区Ge组分HBT相比, 具有更高的特征频率f_T, 且电流增益β和f_T随温度变化变弱, 这有利于防止器件在宽温区工作时电学特性的漂移.同时, 器件整体温度有所降低, 但器件各指温度分布均匀性较差.考虑多指HBT各发射极指散热能力存在差异, 在器件纵向结构设计为基区Ge组分阶梯分布的同时, 对其横向版图进行发射极指间距渐变结构设计, 用于改善器件各指温度分布的均匀性, 进而提高HBT的热稳定性.结果表明, 与基区Ge组分为均匀分布的等发射极指间距结构HBT相比, 新器件各指温度分布均匀性明显改善, f_T保持了较高的值, 且β和f_T 随温度变化不敏感, 热不稳定性得到显著改善, 显示了新器件在宽温区大电流下工作的优越性. 关键词： SiGe 异质结双极晶体管 Ge组分分布 发射极指间距渐变技术 热稳定性     

锗硅异质结晶体管单粒子效应激光微束模拟

对国产锗硅异质结双极晶体管(SiGe HBT)进行了单粒子效应激光微束辐照试验,观测SiGe HBT单粒子效应的敏感区域,测试不同外加电压和不同激光能量下SiGe HBT集电极瞬变电流和电荷收集情况,并结合器件结构对试验结果进行分析。试验结果表明:国产SiGe HBT位于集电极/衬底结内的区域对单粒子效应敏感,波长为1064 nm的激光在能量约为1.5 nJ时诱发SiGe HBT单粒子效应,引起电流瞬变。入射激光能量增强,电流脉冲增大,电荷收集量增加;外加电压增大,电流脉冲的波峰增大;SiGe HBT的单粒子效应与外加电压大小和入射激光能量都相关,电压主要影响瞬变电流的峰值,而电荷收集量主要依赖于入射激光能量。     

MEH-PPV/Alq_3-based bulk heterojunction photodetector

In this paper, we present the effect of varied illumination levels on the electrical properties of the organic blend bulk heterojuction （BHJ） photodiode. To prepare the BHJ blend, poly（2-methoxy-5（2P-ethylhexyloxy） phenyleneviny- lene （MEH-PPV） and aluminum-tris-（8-hydroxyquinoline） （Alq3） are used as donor and acceptor materials, respectively. In order to fabricate the photodiode, a 40-nm thick film of poly（3, 4-ethylendioxytbiophene）：poly（styrensulfonate） （PE- DOT：PSS） is primarily deposited on a cleaned ITO coated glass substrate by spin coating technique. The organic photo- sensitive blend is later spun coated on the PEDOT：PSS layer, followed by the lithium fluoride （LiF） and aluminium （A1） thin films deposition by thermal evaporation. The optical properties of the MEH-PPV：Alq3 blend thin films are investigated using photoluminescence （PL） and UV-Vis spectroscopy. The photodiode shows good photo-current response as a function of variable illumination levels. The responsivity value - 8 mA/W at 3 V is found and the ratio of photo-current to dark current （lph/IDark） is found to be 1.24.     

Direct measurement of the interfacial barrier height of the manganite p–n heterojunction

A manganite p-n heterojunction composed of Lao.67Sro.33MnO3 film and 0.05 wt% Nb-doped SrTiO3 substrate is fabricated. Rectifying behavior of the junction well described by the Shockley equation is observed, and the transport properties of the interface are experimentally studied. A satisfactorily logarithmic linear dependence of resistance on temperature is observed in a temperature range of 150 K-380 K, and the linear relation between bias and activation energies deduced from the R - lIT curves is observed. According to activation energy, the interfacial barrier of the heterojunction is obtained, which is 0.91 eV.     

A novel high performance TFS SJ IGBT with a buried oxide layer

A novel high performance trench field stop(TFS) superjunction(SJ) insulated gate bipolar transistor(IGBT) with a buried oxide(BO) layer is proposed in this paper. The BO layer inserted between the P-base and the SJ drift region acts as a barrier layer for the hole-carrier in the drift region. Therefore, conduction modulation in the emitter side of the SJ drift region is enhanced significantly and the carrier distribution in the drift region is optimized for the proposed structure. As a result, compared with the conventional TFS SJ IGBT(Conv-SJ), the proposed BO-SJ IGBT structure possesses a drastically reduced on-state voltage drop(Vce(on)) and an improved tradeoff between Vce(on)and turn-off loss(Eoff), with no breakdown voltage(BV) degraded. The results show that with the spacing between the gate and the BO layer Wo = 0.2 μm, the thickness of the BO layer Lo = 0.2 μm, the thickness of the drift region Ld = 90 μm, the half width and doping concentration of the N- and P-pillars Wn = Wp = 2.5 μm and Nn = Np = 3 × 1015cm-3, the Vce(on)and Eoffof the proposed structure are 1.08 V and 2.81 mJ/cm2with the collector doping concentration Nc = 1×1018cm-3and 1.12 V and1.73 mJ/cm2with Nc = 5 × 1017cm-3, respectively. However, with the same device parameters, the Vce(on)and Eofffor the Conv-SJ are 1.81 V and 2.88 mJ/cm2with Nc = 1 × 1018cm-3and 1.98 V and 2.82 mJ/cm2with Nc = 5 × 1017cm-3,respectively. Meanwhile, the BV of the proposed structure and Conv-SJ are 1414 V and 1413 V, respectively.     

Substrate bias effects on collector resistance in SiGe heterojunction bipolar transistors on thin film silicon-on-insulator

An analytical expression for the collector resistance of a novel vertical SiGe heterojunction bipolar transistor(HBT) on thin film silicon-on-insulator(SOI) is obtained with the substrate bias effects being considered.The resistance is found to decrease slowly and then quickly and to have kinks with the increase of the substrate-collector bias,which is quite different from that of a conventional bulk HBT.The model is consistent with the simulation result and the reported data and is useful to the frequency characteristic design of 0.13 μm millimeter-wave SiGe SOI BiCMOS devices.     

一种新型Si/SiGe/Si双异质结PIN电学调制结构的异质结能带分析

PIN结构是电光调制器中常见的一种电学调制结构, 该结构中载流子注入效率直接影响着电光调制器的性能. 在前期的研究中, 我们在SOI材料的基础上提出了一种新型Si/SiGe/Si双异质结PIN电学调制结构, 可以有效提高载流子注入效率, 降低调制功耗. 为了进一步研究这种新型调制器结构的调制机理, 本文从单异质结能带理论出发, 定量分析了该新型结构中双异质结的势垒高度变化, 给出了双异质结势垒高度的定量公式, 将新型结构与SiGe-OI和SOI两种PIN电学调制结构进行能带对比, 分析了该新型结构载流子注入增强的原因, 最后模拟了新型结构的能带分布, 以及能带和调制电压与注入载流子密度的关系, 并与SiGe-OI和SOI两种PIN电学调制结构进行对比发现, 1 V调制电压下, 新型结构的载流子密度达到了8× 10¹⁸cm^-3, 比SOI 结构的载流子密度高了800%, 比SiGe-OI结构的载流子密度高了340%, 进一步说明了该新型结构的优越性, 并且验证了理论分析的正确性.     

pn结电容-电压法测量应变SiGe禁带宽度

利用应变SiGe/Si异质pn结电容-电压（C-V）特性确定SiGe禁带宽度的技术.该技术根据SiGe/Si异质pn结C-V实验曲线，计算出 pn结接触电势差，并得到SiGe/Si的价带偏移量和导带偏移量，进而求得SiGe禁带宽度.该技术测试方法简便，其过程物理意义清晰，既适用于分立的SiGe/Si异质pn结，也可直接分析SiGe/Si异质结器件中的SiGe 禁带宽度.实验结果与理论计算及其他相关文献报道的结果符合较好. 关键词： SiGe/Si 异质pn结 C-V 禁带宽度     

含有本征SiGe层的SiGe异质结双极晶体管集电结耗尽层宽度模型

本文分别建立了含有本征SiGe层的SiGe HBT(异质结双极晶体管)集电结耗尽层各区域的电势、电场分布模型,并在此基础上,建立了集电结耗尽层宽度和延迟时间模型,对该模型进行了模拟仿真,定量地分析了SiGe HBT物理、电学参数对集电结耗尽层宽度和延迟时间的影响,随着基区掺杂浓度和集电结反偏电压的提高,集电结耗尽层延迟时间也随之增大,而随着集电区掺杂浓度的提高和基区Ge组分增加,集电结耗尽层延迟时间随之减小. 关键词： SiGe HBT 集电结耗尽层 延迟时间     

A novel 4H-SiC lateral bipolar junction transistor structure with high voltage and high current gain

In this paper, a novel structure of a 4H-SiC lateral bipolar junction transistor (LBJT) with a base field plate and double RESURF in the drift region is presented. Collector-base junction depletion extension in the base region is restricted by the base field plate. Thin base as well as low base doping of the LBJT therefore can be achieved under the condition of avalanche breakdown. Simulation results show that thin base of 0.32 μm and base doping of 3×1017 cm-3 are obtained, and corresponding current gain is as high as 247 with avalanche breakdown voltage of 3309 V when the drift region length is 30 μm. Besides, an investigation of a 4H-SiC vertical BJT (VBJT) with comparable breakdown voltage (3357 V) shows that the minimum base width of 0.25 μm and base doping as high as 8×1017 cm-3 contribute to a maximum current gain of only 128.     

Weak avalanche multiplication in SiGe heterojunction bipolar transistors on thin film silicon-on-insulator

In this paper, we propose an analytical avalanche multiplication model for the next generation of SiGe silicon-on-insulator (SOI) heterojunction bipolar transistors (HBTs) and consider their vertical and lateral impact ionizations for the first time. Supported by experimental data, the analytical model predicts that the avalanche multiplication governed by impact ionization shows kinks and the impact ionization effect is small compared with that of the bulk HBT, resulting in a larger base-collector breakdown voltage. The model presented in the paper is significant and has useful applications in the design and simulation of the next generation of SiGe SOI BiCMOS technology.     

A novel type of ultra fast and ultra soft recovery SiGe/Si heterojunction power diode with an ideal ohmic contact

A novel type of p^+(SiGe)－n^-－n^+ heterojunction switching power diode with high-speed capability is presented to overcome the drawbacks of existing power diodes. The improvement is achieved by using a p^+－n^+ mosaic layer as a substitute for the n^+ region in the conventional p^+(SiGe)－n^-－n^+ diode to realize an `ideal ohmic' contact for electrons and holes simultaneously. Compared with conventional p^+(SiGe)－n^-－n^+ diodes, the ideal ohmic contact p^+(SiGe)－n^-－n^+ diodes have about one third of the reverse recovery time and a half of peak reverse recovery current. Furthermore, the softness factor increases nearly two times and the leakage current decreases 1－2 orders of magnitude. These improvements are achieved without resorting special process step to lower the carrier lifetime and thus the devices could be easily integrated into power ICs. The Ge percentage content of p^+(SiGe) layer is an important parameter for the optimal device design.     

Analytical base–collector depletion capacitance in vertical SiGe heterojunction bipolar transistors fabricated on CMOS-compatible silicon on insulator

The base--collector depletion capacitance for vertical SiGe npn heterojunction bipolar transistors (HBTs) on silicon on insulator (SOI) is split into vertical and lateral parts. This paper proposes a novel analytical depletion capacitance model of this structure for the first time. A large discrepancy is predicted when the present model is compared with the conventional depletion model, and it is shown that the capacitance decreases with the increase of the reverse collector--base bias--and shows a kink as the reverse collector--base bias reaches the effective vertical punch-through voltage while the voltage differs with the collector doping concentrations, which is consistent with measurement results. The model can be employed for a fast evaluation of the depletion capacitance of an SOI SiGe HBT and has useful applications on the design and simulation of high performance SiGe circuits and devices.