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1.
主要对InP/InGaAs异质结进行数值仿真。考虑到异质结界面存在导带不连续和价带不连续,在流体动力学模型的基础上,采用热电子发射模型和隧穿模型,对异质结的直流特性进行仿真。结果表明,热电子发射效应和隧穿效应对异质结界面载流子的输运有很大影响。仿真结果与实验结果基本一致。  相似文献   

2.
采用直流磁控溅射技术制备了Si衬底上的非晶GaN薄膜.GaN肖特基二极管伏安曲线不能简单地用包含串联电阻和复合电流效应的热电子发射理论来解释,其他电流输运机制(空间电荷限制电流)起主要作用.分析数据得到平衡时的电子浓度为1.1×104cm-3和位于Ec-0.363eV的陷阱能级.测量空间电荷限制电流可以用来研究宽带隙化合物非晶半导体GaN的深能级性质.  相似文献   

3.
制备了与AlGaN/GaN高电子迁移率晶体管栅极结构与性能等效的圆形肖特基二极管结构,测量了器件的变温电流-电压特性,研究其在正向与反向偏压条件下的载流子输运过程。结果表明:(1)正向低偏压线形区的电流主要为缺陷辅助隧穿电流,而体电阻效应显著的高偏压区,经典热发射机制占主导地位;(2)AlGaN势垒层中的极化电场对器件的反向漏电流起重要作用,载流子的主要输运过程为Frenkel-Poole发射机制。  相似文献   

4.
采用直流磁控溅射技术制备了Si衬底上的非晶GaN薄膜.GaN肖特基二极管伏安曲线不能简单地用包含串联电阻和复合电流效应的热电子发射理论来解释,其他电流输运机制(空间电荷限制电流)起主要作用.分析数据得到平衡时的电子浓度为1.1×104cm-3和位于Ec-0.363eV的陷阱能级.测量空间电荷限制电流可以用来研究宽带隙化合物非晶半导体GaN的深能级性质.  相似文献   

5.
利用室温下反应磁控溅射的方法在p-Si(100)衬底上制备了HfO2栅介质层,研究了HfO2高k栅介质的电流传输机制和应力引起泄漏电流(SILC)效应.对HfO2栅介质泄漏电流输运机制的分析表明,在电子由衬底注入的情况下,泄漏电流主要由Schottky发射机制引起,而在电子由栅注入的情况下,泄漏电流由Schottky发射和Frenkel-Poole发射两种机制共同引起.通过对SILC的分析,在没有加应力前HfO2/Si界面层存在较少的界面陷阱,而加上负的栅压应力后在界面处会产生新的界面陷阱,随着新产生界面陷阱的增多,这时在衬底注入的情况下,电流传输机制就不仅仅是由Schottky发射机制引起,而存在Frenkel-Poole发射机制起作用.同时研究表明面积对SILC效应的影响很小.  相似文献   

6.
采用直流磁控溅射技术制备了Si衬底上的非晶GaN薄膜. GaN肖特基二极管伏安曲线不能简单地用包含串联电阻和复合电流效应的热电子发射理论来解释,其他电流输运机制(空间电荷限制电流)起主要作用. 分析数据得到平衡时的电子浓度为1.1E4cm-3和位于EC-0.363eV的陷阱能级. 测量空间电荷限制电流可以用来研究宽带隙化合物非晶半导体GaN的深能级性质.  相似文献   

7.
研究了无凹槽AlGaN/GaN肖特基势垒二极管(SBD)的正向电流输运机制。分别采用Ni/Au和TiN作为阳极金属材料制备了无凹槽AlGaN/GaN SBD,对比了两种SBD的直流特性。并通过测量器件的变温I-V特性,研究了器件的正向电流输运机制。结果表明,TiN-SBD(0.95 V@1 mA·mm-1)与Ni/Au-SBD(1.15 V@1 mA·mm-1)相比实现了更低的开启电压,从而改善了正向导通特性。研究发现两种SBD的势垒高度和理想因子都强烈依赖于环境温度,通过引入势垒高度的高斯分布模型解释了这种温度依赖性,验证了正向电流输运机制为与势垒高度不均匀分布相关的热电子发射机制。  相似文献   

8.
利用室温下反应磁控溅射结合炉退火的方法在P-Si(100)衬底上制备了Al2O3栅介质层,研究了不同的溅射气氛和退火条件对Al2O3栅介质层物理特性的影响.结果表明:在较高温度下N2气氛中退火有助于减小泄漏电流;在O2气氛中退火有助于减少Al2O3栅介质中的氧空位缺陷.对Al2O3栅介质泄漏电流输运机制的分析表明,在电子由衬底注入的情况下,泄漏电流主要由Schottky发射机制引起,而在电子由栅注入的情况下,泄漏电流可能由Schottky发射和Frenkel-Poole发射两种机制共同引起.  相似文献   

9.
Al_2O_3栅介质的制备工艺及其泄漏电流输运机制   总被引:4,自引:0,他引:4  
利用室温下反应磁控溅射结合炉退火的方法在P Si(10 0 )衬底上制备了Al2 O3 栅介质层,研究了不同的溅射气氛和退火条件对Al2 O3 栅介质层物理特性的影响.结果表明:在较高温度下N2 气氛中退火有助于减小泄漏电流;在O2 气氛中退火有助于减少Al2 O3 栅介质中的氧空位缺陷.对Al2 O3 栅介质泄漏电流输运机制的分析表明,在电子由衬底注入的情况下,泄漏电流主要由Schottky发射机制引起,而在电子由栅注入的情况下,泄漏电流可能由Schot tky发射和Frenkel Poole发射两种机制共同引起.  相似文献   

10.
通过对异质结材料上制作的肖特基结构变温C-V测量和传输线模型变温测量,研究了蓝宝石衬底AlGaN/GaN异质结高电子迁移率晶体管的直流特性在25~200℃之间的变化,分析了载流子浓度分布、沟道方块电阻、欧姆比接触电阻和缓冲层泄漏电流随温度的变化规律.得出了器件饱和电流随温度升高而下降主要由输运特性退化造成,沟道泄漏电流随温度的变化主要由栅泄漏电流引起的结论.同时,证明了GaN缓冲层漏电不是导致器件退化的主要原因.  相似文献   

11.
An analysis of carrier transport in n- and p-type distributed Bragg reflectors (DBR) of vertical-cavity surface-emitting lasers that consist of stacks of quarter-wave GaAs-AlAs layers is presented. The analysis is based on the diffusion-drift approximation with the thermionic boundary conditions at heterojunction interfaces. The spatial distribution of carrier effective masses and mobilities has been taken into account. While the voltage drop in n-type DBR is determined mostly by thermionic emission at the interfaces, the drift-diffusion component of the voltage drop is comparable with the thermionic emission in p-type DBR. We present the calculated resistance as a function of graded-region thicknesses and doping levels, which can be useful for low-resistive DBR design  相似文献   

12.
本文把在金属-半导体接触中同时存在着扩散和热电子发射这样两种互相串联的电流传输机构这一看法推广到了异质结。以GaAs-Ge为例进行了计算,结果表明,对于不同掺杂的异质结,电流传输机构也不尽相同:有的象一个纯扩散机构的结,而另一些必须用热电子发射模型来描述。计算结果还预示,以扩散限制为主的异质结在正向Ⅰ—Ⅴ特性中将出现负阻,文中对此现象提出了一种物理解释。 文章最后对整个研究作了小结。提出新模型的讨论可能有助于对ΔE。测试结果进行合理的修正,对异质结伏—安特性进行合理的解释;也可能有助于建立各种情况下半导体内的边界条件,以及有助于澄清在np乘积和内建势等方面存在的理论上的争论。  相似文献   

13.
A closed-form expression for the current-voltage characteristics of isotype heterojunctions is developed. Unlike previous treatments of this problem which considered only thermionic emission, this theory, in analogy to metal-semiconductor theory, includes both transport by thermionic emission across the interface and by drift-diffusion in the space charge region. A representative isotype heterojunction is analyzed and it is found that both transport mechanisms must be considered when calculating the current-voltage characteristics.  相似文献   

14.
基于结终端扩展的4H-SiC肖特基势垒二极管研制   总被引:1,自引:1,他引:0  
采用高真空电子束热蒸发金属Ni分别作肖特基接触和欧姆接触,离子注入形成结终端扩展表面保护,研制出Ni/4H-SiC肖特基势垒二极管(SBD)。I-V特性测量说明,Ni/4H-SiCSBD有较好的整流特性,热电子发射是其主要的运输机理。实验测量其反向击穿电压达1800V,且反向恢复特性为32ns。  相似文献   

15.
采用微电子平面工艺,高真空电子束热蒸发金属Ni分别作肖特基接触和欧姆接触,二级场限环终端表面保护,研制出Ni/4H-SiC肖特基势垒二极管(SBD)。I-V特性测量说明,Ni/4H-SiCSBD有较好的整流特性,热电子发射是其主要的运输机理。反向击穿电压达1500V,理想因子为1.2,肖特基势垒高度为0.92eV。  相似文献   

16.
The technology for ohmic contacts to group III–V compound semiconductors is reviewed in this paper. The basic principles of current transport in metal-semiconductor (Schottky barrier) contacts are presented first. The modes of current transport considered are thermionic emission over the barrier, and tunneling through the barrier due to thermionic-field or field emission. Special attention is devoted to the parameters of temperature and doping concentration which determine the dominant mode of conduction. As the primary mode of conduction changes from thermionic emission dominated to tunneling dominated, the current-voltage behavior of the contact changes from rectifying to ohmic in character. The experimental techniques for fabricating ohmic contacts to III–V compound semiconductors are then described. Contact problems as they pertain to specific device applications are considered. Finally, present difficulties with contacts to mixed III–V crystals are discussed.  相似文献   

17.
An overview of ohmic contacts on solar cells is presented. The fundamentals of metal-semiconductor contacts are reviewed, including the Schottky approach, Fermi level pinning by surface states, and the mechanisms of thermionic emission, thermionic/field emission, and tunneling for current transport. The concept of contact resistance is developed and contact resistance data for several different contact materials on both silicon and gallium arsenide over a range of doping densities are summarized. Finally, the requirements imposed by solar cells on contact resistance are detailed.  相似文献   

18.
Carrier transport in pn-junction is re-examined using McKelvey's flux method. A simple but physically based treatment of carrier transport leads to new expressions for the "law of the junction," quasi-Fermi level, I-V characteristics, base transit time, and probability of carrier backscattering from the space charge region, which are valid from the ballistic through the diffusive regimes. Comparison with Monte Carlo simulation shows that the deduced backscattering rate well describes the bias dependence. For silicon pn-junctions, the backscattering rate under reverse bias conditions is less than 5%, satisfying the Bethe condition of thermionic emission, while it rapidly increases with forward bias until drift-diffusion governs the transport. The effect of thin-base transport and backscattering on the current, carrier velocity, and distribution function is also investigated. It is found that for a base thickness less than 50 nm even silicon transistors enter the quasi-ballistic transport regime. These results should prove useful not only for fundamental understanding of the pn-junction transport, but also for careful design of advanced transistors.<>  相似文献   

19.
We report on the drift-diffusion based simulation of a wurtzite (WZ) GaN MESFET. The main emphasis is put on the influence of electron mobility modeling on DC current-voltage (I-V) characteristics of the WZ-GaN MESFET. Two different analytical expressions are used for the electron mobility as a function of electric field. The first model is based on a simple saturation of the steady-state drift velocity with electric field (conventional three-parameter model). The other model is more realistic since it well reproduces the drift velocity-field characteristics obtained by Monte Carlo (MC) calculations, revealing the peak drift velocity with subsequent saturation at higher electric fields. Thus, it should be implemented in the drift-diffusion model for a following device simulation. However, the MC electron transport data for WZ-GaN are influenced by the specific choice of the material and band structure parameters, resulting in a variation of drift velocity-field characteristics. In addition, it should be noted that the MC simulation also neglects crystal defects in GaN, which, for example, might lead to uncontrolled electron compensation and additional electron scattering. In the present study we show that the DC I-V characteristics of the WZ-GaN MESFET are strongly affected by the MC-like electron mobility model, in particular by the peak steady-state velocity and the shape of the velocity-field characteristics even for the same drift velocity saturation level  相似文献   

20.
In a Schottky diode, the diode saturation current is controlled by the barrier height at the metal and semi-conductor contact, assuming that the dominant current is due to thermionic emission. When ion implantation is used to increase the barrier height, both thermionic emission and drift-diffusion of carriers become important in calculating the current. Numerical methods are used in solving Poisson's equation and the current continuity equations for an ion implanted doping profile. The electron and hole current in the surface region are calculated as a function of the total implantation dosage. The results show that the decrease of saturation current and the increase of effective barrier height in an ion implanted diode is mainly due to the suppression of the thermionic emission current by the implanted impurity atoms, rendering the diode to act like a pn junction.  相似文献   

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