Numerical Simulation and Analysis of Bipolar Junction Photogate Transistor for CMOS Image Sensor

A new photodetector--bipolar junction photogate transistor is presented for CMOS image sensor and its analytical model is also established.With the technical parameter of the 0.6μm CMOS process,the bipolar junction photogate transistor is analyzed and simulated.The simulated results illustrate that the bipolar junction photogate transistor has the similar characteristics of the traditional photogate transistor.The photocurrent density of the bipolar junction photogate transistor increases exponentially with the incidence light power due to introducing the injection p+n junction.Its characteristic of blue response is rather improved compared to the traditional photogate transistor that benefits to increase the color photograph made up of the red,the green,and the blue.

Machine learning-based analyses for total ionizing dose effects in bipolar junction transistors

Machine learning methods have proven to be powerful in various research fields.In this paper,we show that research on radiation effects could benefit from such methods and present a machine learning-based scientific discovery approach.The total ionizing dose(TID)effects usually cause gain degradation of bipolar junction transistors(BJTs),leading to functional failures of bipolar integrated circuits.Currently,many experiments of TID effects on BJTs have been conducted at different laboratories worldwide,producing a large amount of experimental data which provides a wealth of information.However,it is difficult to utilize these data effectively.In this study,we proposed a new artificial neural network(ANN)approach to analyze the experimental data of TID effects on BJTs An ANN model was built and trained using data collected from different experiments.The results indicate that the proposed ANN model has advantages in capturing nonlinear correlations and predicting the data.The trained ANN model suggests that the TID hardness of a BJT tends to increase with base current I.A possible cause for this finding was analyzed and confirmed through irradiation experiments.

Two-dimensional analysis of the interface state effect on current gain for a 4H-SiC bipolar junction transistor

This paper studies two-dimensional analysis of the surface state effect on current gain for a 4H-SiC bipolar junction transistor （BJT）. Simulation results indicate the mechanism of current gain degradation, which is surface Fermi level pinning leading to a strong downward bending of the energy bands to form the channel of surface electron recombination current. The experimental results are well-matched with the simulation, which is modeled by exponential distributions of the interface state density replacing the single interface state trap. Furthermore, the simulation reveals that the oxide quality of the base emitter junction interface is very important for 4H-SiC BJT performance.

Radiation-induced 1/f noise degradation of PNP bipolar junction transistors at different dose rates

It is found that ionizing-radiation can lead to the base current and the 1/f noise degradations in PNP bipolar junction transistors. In this paper, it is suggested that the surface of the space charge region of the emitter-base junction is the main source of the base surface 1/f noise. A model is developed which identifies the parameters and describes their interactive contributions to the recombination current at the surface of the space charge region. Based on the theory of carrier number fluctuation and the model of surface recombination current, a 1/f noise model is developed. This model suggests that 1/f noise degradations are the result of the accumulation of oxide-trapped charges and interface states. Combining models of ELDRS, this model can explain the reason why the 1/f noise degradation is more severe at a low dose rate than at a high dose rate. The radiations were performed in a Co60 source up to a total dose of 700 Gy（Si）. The low dose rate was 0.001 Gy（Si）/s and the high dose rate was 0.1 Gy（Si）/s. The model accords well with the experimental results.

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 tield 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 ~tm and base doping as high as 8 × 10^17 cm^-3 contribute to a maximum current gain of only 128.

Bulk and surface damages in complementary bipolar junction transistors produced by high dose irradiation

Two complementary types NPN and PNP of bipolar junction transistors （BJTs） were exposed to higll dose of neutrons and gamma rays. The change in the base and collector currents, minority carriers lifetime, and current gain factor/3 with respect to the dose were analyzed. The contributions of the base current according to the defect types were also reported. It was declared that the radiation effect of neutrons was almost similar between the two transistor types, this effect at high dose may decrease the value of/3 to less than one. The Messenger-Spratt equation was used to describe the experimental results in this case. However, the experimental data demonstrated that the effect of gamma rays was generally higher on NPN than PNP transistors. This is mainly attributed to the difference in the behavior of the trapped positive charges in the SiO2 layers. Meanwhile, this difference tends to be small for high gamma dose.

Fabrication and characterization of 4H-SiC bipolar junction transistor with double base epilayer

In this paper we report on a novel structure of a 4H-SiC bipolar junction transistor with a double base epilayer that is continuously grown. The measured dc common-emitter current gain is 16.8 at Ic = 28.6 mA （Jc = 183.4 A/cm2）, and it increases with the collector current density increasing. The specific on-state resistance （Rsp-on） is 32.3 mΩ.cm2 and the open-base breakdown voltage reaches 410 V. The emitter N-type specific contact resistance and N＋ emitter layer sheet resistance are 1.7× 10-3 Ω.cm2 and 150 Ω/□, respectively.

Low Gate Voltage Operated Multi-emitter-dot H^+ Ion-Sensitive Gated Lateral Bipolar Junction Transistor

A low gate voltage operated multi-emitter-dot gated lateral bipolar junction transistor （BJT） ion sensor is proposed. The proposed device is composed of an arrayed gated lateral BJT, which is driven in the metal-oxidesemiconductor field-effect transistor （MOSFET）-BJT hybrid operation mode. Further, it has multiple emitter dots linked to each other in parallel to improve ionic sensitivity. Using hydrogen ionic solutions as reference solutions, we conduct experiments in which we compare the sensitivity and threshold voltage of the multi-emitter-dot gated lateral BJT with that of the single-emitter-dot gated lateral BJT. The multi-emitter-dot gated lateral BJT not only shows increased sensitivity but, more importantly, the proposed device can be operated under very low gate voltage, whereas the conventional ion-sensitive field-effect transistors cannot. This special characteristic is significant for low power devices and for function devices in which the provision of a gate voltage is difficult.

Radiation effects of 50-MeV protons on PNP bipolar junction transistors

The effects of radiation on 3 CG110 PNP bipolar junction transistors(BJTs)are characterized using 50-Me V protons,40-Me V Si ions,and 1-Me V electrons.In this paper,electrical characteristics and deep level transient spectroscopy(DLTS)are utilized to analyze radiation defects induced by ionization and displacement damage.The experimental results show a degradation of the current gain and an increase in the types of radiation defect with increasing fluences of 50-Me V protons.Moreover,by comparing the types of damage caused by different radiation sources,the characteristics of the radiation defects induced by irradiation show that 50-Me V proton irradiation can produce both ionization and displacement defects in the 3 CG110 PNP BJTs,in contrast to 40-Me V Si ions,which mainly generate displacement defects,and 1-Me V electrons,which mainly produce ionization defects.This work provides direct evidence of a synergistic effect between the ionization and displacement defects caused in PNP BJTs by 50-Me V protons.

Thermal analytic model of current gain for bipolar junction transistor-bipolar static induction transistor compound device

This paper proposes a thermal analytical model of current gain for bipolar junction transistor-bipolar static induction transistor （BJT-BSIT） compound device in the low current operation. It also proposes a best thermal compensating factor to the compound device that indicates the relationship between the thermal variation rate of current gain and device structure. This is important for the design of compound device to be optimized. Finally, the analytical model is found to be in good agreement with numerical simulation and experimental results. The test results demonstrate that thermal variation rate of current gain is below 10% in 25 ℃-85 ℃ and 20% in -55 ℃-25 ℃.

The Bipolar Field-Effect Transistor:Ⅰ.Electrochemical Current Theory(Two-MOS-Gates on Pure-Base)

This paper describes the bipolar field-effect transistor （BiFET） and its theory. Analytical solution is ob- tained from partitioning the two-dimensional transistor into two one-dimensional transistors. The analysis employs the parametric surface-electric-potential and the electrochemical （quasi-Fermi） potential-gradient driving force to compute the current. Output and transfer D. C. current and conductance versus voltage are presented over practi- cal ranges of terminal D. C. voltages and device parameters. Electron and hole surface channel currents are pres- ent simultaneously, a new feature which could provide circuit functions in one physical transistor such as the CMOS inverter and SRAM memory.

BJT等效电路模型的发展

随着BJT尺寸的缩小以及BJT广泛应用于高速和RF电路,有效及准确的BJT电路设计要求更加精确的等效电路模型。通过介绍模型的基本原理及其对BJT器件关键物理效应的模拟,描述不同模型开发者采用的方式,结合仿真结果分析不同模型的特点。主要从以下几个方面展开:模型的大信号等效电路图;归一化电荷的计算,转移电流表达式;晶体管二阶效应模型,包括基区宽度调制效应(即Early效应)、大注入效应等;大电流条件下的Kirk效应,准饱和效应等。

开关用BJT的特性研究和PSPICE仿真

在Marx脉冲功率发生器中,开关是最重要的组件,其特性直接影响输出脉冲上升沿。提出一种利用BJT(Bipolar Junction Transistor)集电极与发射极间的雪崩击穿特性的新型开关器件代替传统开关的方法,可实现Marx输出上升沿小于5ns的脉冲电压,可代替传统Marx发生器中的气体开关。介绍不同型号的BJT集电极与发射极间雪崩击穿特性,根据实验结果,以适合小型Marx发生器的BJT开关特性为主要依据选用合适的BJT。目前没有雪崩击穿的仿真元件,只能用PSPICE建立BJT的集电极与发射极间击穿仿真模型代替实际BJT的雪崩击穿,并以此来辅助Marx脉冲发生器的设计。

4H-SiC npn BJT特性研究

基于二维器件仿真软件Medici对 4H SiC双极型晶体管 (BJT)进行了建模 ,包括能带模型、能带窄变模型、迁移率模型、产生复合模型和不完全电离模型 ,为 4H SiC的工艺与器件提供了设计平台 .在此基础上对 4H SiCBJT器件进行了模拟研究 .结果显示 ,器件基极电流IB=1μA/μm时发射极电流增益 β为 32 .4 ,击穿电压BVCEO大于 80 0V ,截止频率fT 接近

基于BJT的ESD保护器件中维持电压的建模与分析

基于双极晶体管（BJT）结构的静电放电（ESD）保护器件具有双向导通特性和良好的保护性能,在ESD保护中应用广泛。鉴于该类器件在负阻效应下维持电压的产生机理和建模方面的研究较少,提出了一种维持电压的数学建模方法。首先分析了多种调制效应对维持电压的影响,优化了模型参数;其次,基于0.6μm BiCMOS工艺对NPN型BJT的结构及电学性能进行了仿真分析,通过数据拟合得到了维持电压的估算模型;最后,制备了两种不同结构的样品并进行了测试,实测数据与估算值的相对误差范围约12%-15%,表明建立的维持电压模型具有较高的可靠性。

利用BJT开关的Marx型脉冲发生器

主要介绍了双极结型晶体管(BJT)的击穿特性,以及作为开关应用时的通断速度。根据实验结果可知,BJT的开关速度在20 ns以内,尤其在基射极短路的情况下,开关速度低于10 ns,是理想的开关元件。最后利用BJT作为开关设计了一个纳秒级Marx型负脉冲发生器,根据实验结果可知,输出脉冲幅值可达2.3 kV,宽度低于10 ns,脉冲下降沿为3 ns。

一种新型4H-SiC BJT结终端结构研究

设计了一种应用于4H-SiC BJT的新型结终端结构。该新型结终端结构通过对基区外围进行刻蚀形成单层刻蚀型外延终端,辅助耐压的p+环位于刻蚀型外延终端的表面,采用离子注入的方式,与基极接触的p+区同时形成。借助半导体数值分析软件SILVACO,对基区外围的刻蚀厚度和p+环的间距进行了优化。仿真分析结果表明,当刻蚀厚度为0.8μm,环间距分别为8,10和9μm时,能获得最高击穿电压。新结构与传统保护环(GR)和传统结终端外延(JTE)相比,BVCEO分别提高了34%和15%。利用该新型终端结构,得到共发射极电流增益β>47、共发射极击穿电压BVCEO为1 570V的4H-SiC BJT器件。

双外延基区4H-SiC BJTs的建模与仿真(英文)

基于4H-SiC的材料特性,对具有双外延基区结构的4H-SiC双极晶体管进行研究.通过分析该结构在基区内部形成的自建电场以及基区渡越时间,利用正交试验的方法,基于各种器件二维模型,对该器件结构进行数值计算,并进行平均极差分析.计算结果表明,该器件的共发射结电流增益最高可达72,具有负温度系数,并且在一个很宽的集电极电流范围内该特性保持不变.

基于BJT开关和Marx的双极性脉冲发生器

双极结型晶体管(BJT)的集电极与发射极之间的雪崩击穿具有快导通、快恢复、高稳定性等优点,适合作为小型Marx脉冲功率发生系统自击穿开关。将相同级数的单层Marx发生器和双层Marx发生器进行了对比,得出相同级数的双极性Marx发生器输出电压的峰值更高,更加稳定;在倍压的情况下,将不同输出负载的放电脉冲进行了对比,得出以8个BJT串联作为负载,更可获得10 ns左右脉宽的窄脉冲。

A novel structure of a high current gain 4H-SiC BJT with a buried layer in the base

In this paper, a new structure of a 4H-SiC bipolar junction transistor （BJT） with a buried layer （BL） in the base is presented. The current gain shows an approximately 100% increase compared with that of the conventional structure. This is attributed to the creation of a built-in electric field for the minority carriers to transport in the base which is explained based on 2D device simulations. The optimized design of the buried layer region is also considered by numeric simulations.