共查询到19条相似文献,搜索用时 156 毫秒
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本文报道GaAs/AlGaAs多量子阱长波长红外探测器材料的制备及其性能.这种材料由GaAs阱和AlGaAs势垒组成,除内n型掺杂,具有50个周期.利用分子束外延技术成功地生长出了大面积(2英寸)均匀(厚度△t_max/≤3%,组分△ x_max/x≤3.4%,掺杂浓度△nmax/n≤3%,椭圆缺陷≤300cm-2)的外延材料.分析了暗电流的成因,通过加厚势垒(Lb≥300)、控制掺杂(n≤1×10 ̄18cm ̄3)、精确设计子带结构,将暗电流降低了几个数量级,同时使电子的输运得到了改善.由此得到了高质量的 相似文献
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本文利用分子束外延(MBE)技术成功生长了GaAs/AlGaAs非均匀量子阱红外探测器材料,并对相关微结构作了细致表征。分析比较了非均匀量子阱结构和常规量子阱红外探测器性能差异,并对比研究了不同势阱宽度下非均匀量子阱红外探测器的性能变化。通过高分辨透射电子显微镜(HRTEM)结合能谱仪(EDS)对非均匀量子阱红外探测器材料微结构进行了分析,并利用二次离子质谱仪(SIMS)对非均匀势阱掺杂进行了表征。结果表明,该量子阱外延材料晶体质量很好,量子阱结构和掺杂浓度也与设计值符合较好。对于非均匀量子阱红外探测器,通过改变每个阱的掺杂浓度和势垒宽度,可以改变量子阱电场分布,而与传统的均匀量子阱红外探测器相比,其暗电流显著下降(约一个数量级)。在不同阱宽下,非均匀量子阱的跃迁模式发生改变,束缚态到准束缚态跃迁模式下(B-QB)的器件具有较高的黑体响应率以及较低的暗电流。 相似文献
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测量了一系列不同隔离层(spacer)厚度、阱宽和硅δ掺杂浓度的单边掺杂的赝形高电子迁移率晶体管(pHEMTs)量子阱的变温和变激发功率光致发光谱,详细研究了(el-hh1)和(e2-hh1)两人发光峰之间的动态竞争发光机制,并运用有限差分法自治求解薛定谔方程和泊松方程以得出电子限制势、子带能极以及相应的电子包络波函数、子带占据几率和δ掺杂电子转移效率,研究了两个峰的相对积分发光强度随隔离层厚度、阱宽和δ掺杂浓度的变化。 相似文献
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利用Silvaco软件对Al0.2Ga0.8N/GaN共振隧穿二极管(RTD)进行仿真,重点研究了InGaN子量子阱结构及相应非对称势垒结构设计对其电流特性的影响。对比分析了子量子阱结构中InGaN的In组分和子阱厚度对RTD微分负阻(NDR)特性的影响,得出了提升器件性能的最佳参数范围。为了克服Al0.2Ga0.8N/GaN RTD势垒低对器件电流峰谷比(PVCR)的影响,在子量子阱结构的基础上引入了非对称势垒结构设计,通过改变收集区侧势垒的高度和厚度,将AlGaN/GaN的Ip和PVCR由基本结构的0.42 A和1.25,提高到了0.583 A和5.01,实现了器件性能的优化,并为今后的器件研制提供了设计思路。 相似文献
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用Matlab程序语言数值计算了多量子阱结构的能级,并研究了量子阱间耦合对其带结构的影响。多量子阱模型是在一个一维有限深势阱(阱边势垒高为 V0)中插入等高(Vb)等厚(b)的势垒方式建成,被分割而成的多量子阱厚度为w。通过增加插入壁垒的个数N、改变阱垒厚度比w/b 及势垒高度比V0/Vb,分别近似计算了对应的结构的能级及波函数。计算结果显示,量子阱间耦合受上述参数的强烈影响,改变参数N,w/b 或V0/Vb ,能带和带隙的宽度是可以被调节的。研究说明,量子阱的能带及带隙宽度达到期望值是完全有可能实现的。 相似文献
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The hot-carrier effects in silicon nitride lightly doped drain (LDD) spacer MOSFETs are discussed. It is found that the oxide thickness under the nitride film spacer affects the hot-carrier effects. The thinner the LDD spacer oxide becomes, the larger the initial drain current degradation becomes at the DC stress test and the smaller the stress time dependence becomes. After the DC stress test, reduced drain current recovers at room temperature. These phenomena are due to the large hot-carrier injection into the LDD nitride spacer, because the nitride film barrier height is much less than the silicon oxide barrier height. Therefore, it is necessary to form the LDD spacer oxide, in order to suppress the large hot-carrier injection in the nitride film LDD spacer MOSFET. The drain current shift mechanism in the nitride spacer MOSFETs is discussed, considering the lucky electron model 相似文献
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AlAs/GaAs/In0.1Ga0.9As/GaAs/AlAs double-barrier resonant tunneling diodes(DBRTDs) grown on a semi-insulated GaAs substrate with molecular beam epitaxy is demonstrated.By sandwiching the In0.1Ga0.9As layer between GaAs layers,potential wells beside the two sides of barrier are deepened,resulting in an increase of the peak-to-valley current ratio (PVCR) and a peak current density.A special shape of collector is designed in order to reduce contact resistance and non-uniformity of the current;as a result the total current density in the device is increased.The use of thin barriers is also helpful for the improvement of the PVCR and the peak current density in DBRTDs.The devices exhibit a maximum PVCR of 13.98 and a peak current density of 89kA/cm2 at room temperature. 相似文献
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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
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In this paper, the metamorphic high electron mobility transistors (mHEMTs) are investigated numerically and compared with pseudo-morphic high electron mobility transistors (pHEMTs). The two-dimensional device simulator, MEDICI, is used to solve the Poisson's equation and the electron/hole current continuity equations. The influences of δ-doping concentration and position, gate width, spacer thickness, etc. on the performances of HEMTs are explored. It shows clearly that mHEMTs have higher transconductances, drain currents and DC voltage swings than pHEMTs. 相似文献
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This paper presents the results of a simulation study focused on the evaluation of the DC characteristics of an n-p-n SiGe-based heterojunction bipolar transistor (HBT) performing an extremely thin n+ hydrogenated amorphous silicon (a-Si:H) emitter. The a-Si:H(n)/SiGe(p) structure exhibits an energy gap difference of approximately 0.8 eV mostly located at the valence band side and this results in an optimal configuration for the emitter/base junction to improve the emitter injection efficiency and thus the device performance.Considering a 20% Ge uniform concentration profile in the base region, simulations indicate that the DC characteristics of an a-Si:H/SiGe HBT are strictly dependent on two essential geometrical parameters, namely the emitter width and the base width. In particular, the emitter thickness degrades device characteristics in terms of current handling capabilities whereas higher current gains are obtained for progressively thinner base regions. A DC current gain exceeding 9000 can be predicted for an optimized device with a thin emitter and a 10 nm-thick, doped base. 相似文献
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This work elucidates the applicability for Liquid-Phase Epitaxy (LPE) to grow epilayers of AlNi2Si on single crystalline Si with a good crystalline quality and low series resistance. Surface morphology and crystalline structural characteristics of the heterojunction were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Temperature dependence of the current–voltage (I–V) characteristics is studied to elucidate the predominant conduction mechanism in the temperature range 305–370 K. Heterojunction parameters such as ideality factor, series resistance, barrier height show temperature dependence in the desired temperature range. Cheung functions are applied for determination the heterojunction parameters and compared with each other. Temperature dependence of capacitance–voltage (C–V) characteristics was considered. The built-in potential, net carrier concentration, maximum barrier height, maximum barrier field and the width of the depletion region obtained from the C–V measurements were studied as a function of temperature. 相似文献
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《Microelectronics Reliability》2015,55(6):890-893
In this work, the InAs/AlSb high electron mobility transistors (HEMTs) on GaAs semi-insulating substrate using refractory iridium (Ir) gate technology was proposed. The Ir-gate exhibited a superior metal work function which was beneficial for increasing Schottky barrier height of InAs/AlSb heterostructures to 0.58 eV. Compared to the Ti-gate HEMT, the Ir-gate HEMT shows higher threshold voltage and lower gate leakage current owing to its higher Schottky barrier height and higher melting point. Moreover, the Ir-gated HEMT also shows the manifest stability improvement of DC characteristics under hot carrier stress as the Ti and As diffusion is alleviated. 相似文献