纳米电子器件及其集成

对基于Top-Down加工技术的纳米电子器件如:单电子器件、共振器件、分子电子器件等的研究现状、面临的主要挑战等进行了讨论.采用CMOS兼容的工艺成功地研制出单电子器件,观察到明显的库仑阻塞效应;在半绝缘GaAs衬底上制作了AlAs/GaAs/In0.1 Ga0.9As/GaAs/AlAs双势垒共振隧穿二极管,采用环型集电极和薄势垒结构研制的共振隧穿器件,在室温下测得其峰谷电流比高达13.98,峰电流密度大于89kA/cm2;概述了交叉阵列的分子存储器的研究进展.     

纳米电子器件及其集成

对基于Top-Down加工技术的纳米电子器件如:单电子器件、共振器件、分子电子器件等的研究现状、面临的主要挑战等进行了讨论.采用CMOS兼容的工艺成功地研制出单电子器件,观察到明显的库仑阻塞效应;在半绝缘GaAs衬底上制作了AlAs/GaAs/In0.1 Ga0.9As/GaAs/AlAs双势垒共振隧穿二极管,采用环型集电极和薄势垒结构研制的共振隧穿器件,在室温下测得其峰谷电流比高达13.98,峰电流密度大于89kA/cm2;概述了交叉阵列的分子存储器的研究进展.     

GaAs基共振隧穿二极管的研究

对GaAs基共振隧穿二极管(RTD)进行了研究,首先用分子束外延(MBE)方法进行AlAs/GaAs/InGaAs双势垒单势阱材料结构的生长.接着用常温光致荧光(PL)方法对结构材料进行了测试分析,其结果显示,较好的外延结构材料的PL谱线半峰宽达到62.6 nm.最后通过制成RTD器件对材料进行验证,器件测试结果表现出良好的直流特性.     

室温下高峰谷电流比、高峰电流密度的双势垒共振隧穿二极管

在半绝缘GaAs衬底上制作了AlAs/GaAs/In0.1Ga0.9As/GaAs/AlAs双势垒共振隧穿二极管.在GaAs层中加入In0.1Ga0.9As层用以降低势垒两边的势阱深度,从而提高了器件的峰谷电流比和峰电流密度.为了减小器件的接触电阻和电流的非均匀性,使用了独特形状的集电极,总的电流密度也因此提高.薄栅也有助于提高器件的PVCR和峰电流密度.在室温下测得其峰谷电流比高达13.98,峰电流密度大于89kA/cm2.     

室温下高峰谷电流比、高峰电流密度的双势垒共振隧穿二极管

在半绝缘GaAs衬底上制作了AlAs/GaAs/In0.1Ga0.9As/GaAs/AlAs双势垒共振隧穿二极管.在GaAs层中加入In0.1Ga0.9As层用以降低势垒两边的势阱深度,从而提高了器件的峰谷电流比和峰电流密度.为了减小器件的接触电阻和电流的非均匀性,使用了独特形状的集电极,总的电流密度也因此提高.薄栅也有助于提高器件的PVCR和峰电流密度.在室温下测得其峰谷电流比高达13.98,峰电流密度大于89kA/cm2.     

肖特基栅共振隧穿三极管(SGRTT)的器件模拟

使用Atlas软件模拟了肖特基栅共振隧穿三极管。通过改变发射极长度、栅极金属和上层AlAs势垒的距离以及靠近AlAs势垒的GaAs层浓度,得到器件耗尽区边界以及所对应的I-V特性,由此分析和解释了器件结构参数对器件特性的影响,最后对器件在电路中的应用予以说明。     

不对称双势垒结构中的非共振磁隧穿现象

本文系统研究了不对称GaAs/AlAs双势垒共振隧穿结构中非共振磁隧穿谱在正反偏压方向上的特征差异,并且用渡越电子沿正反方向隧穿通过双势垒结构时在势阱中停留时间的不同合理解释了实验结果。     

RTD在压力下的弛豫振荡特性

报道了共振隧穿二极管(RTD)在压力下的弛豫振荡特性.采用Pspice 8.0软件仿真并设计了振荡电路,测得其振荡频率达200kHz.在(100)半绝缘(SI)GaAs衬底上利用分子束外延(MBE)技术生长了AlAs/InxGa1-xAs/GaAs双势垒共振隧穿结构(DBRTS),并采用Au/Ge/Ni/Au金属化和空气桥结构成功加工出了RTD.由于RTD的压阻效应,采用显微喇曼光谱仪标定所加应力大小,对RTD在加压条件下的振荡特性进行了研究,结果表明其弛豫振荡频率大致有-17.9kHz/MPa的改变量.     

RTD在压力下的弛豫振荡特性

报道了共振隧穿二极管(RTD)在压力下的弛豫振荡特性.采用Pspice 8.0软件仿真并设计了振荡电路,测得其振荡频率达200kHz.在(100)半绝缘(SI)GaAs衬底上利用分子束外延(MBE)技术生长了AlAs/InxGa1-xAs/GaAs双势垒共振隧穿结构(DBRTS),并采用Au/Ge/Ni/Au金属化和空气桥结构成功加工出了RTD.由于RTD的压阻效应,采用显微喇曼光谱仪标定所加应力大小,对RTD在加压条件下的振荡特性进行了研究,结果表明其弛豫振荡频率大致有-17.9kHz/MPa的改变量.     

GaAs基共振隧穿微加速度计的研究

研究了一种新型的GaAs基压阻式共振隧穿微加速度计结构.该微加速度计的压敏元件采用AlAs/In0.1Gao.9As双势垒共振隧穿纳米薄膜结构.加速度计的压敏元件和悬臂梁的加工分别利用空气桥工艺和控制孔工艺.对加工出来的加速度计结构进行振动台实验,初步测得传感器的灵敏度为7.6 mV/g,线性度为0.16%.     

A DBRTD with a High PVCR and a Peak Current Density at Room Temperature

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.     

Power and stability limitations of resonant tunneling diodes

Stability criteria for resonant tunneling diodes are investigated. Details of how extrinsic elements, such as series inductance and parallel capacitance, affect the stability are presented. A GaAs/AlAs/InGaAs/AlAs/GaAs double-barrier diode is investigated, showing the effect of different modes of low-frequency oscillation and the extrinsic circuit required for stabilization. The effect of device stabilization on high-frequency power generation is described. The main conclusions of the paper are: (1) stable resonant tunneling diode operation is difficult to obtain, and (2) the circuit and device conditions required for stable operation greatly reduce the amount of power that can be produced by these devices     

Epitaxial liftoff of AlAs/GaAs double barrier resonant tunnelling diodes

For the first time, the successful removal of AlAs/GaAs double barrier resonant tunnelling diodes from the substrate using the epitaxial liftoff technique is reported. Ohmic contacts were formed to the top and bottom of the devices, using indium-alloyed ohmic contacts for the backside of the lifted-off diodes. Room temperature peak-to-valley ratios of 3.4 with peak current densities of 50 kA/cm/sup 2/ were obtained.<>     

Combined two-band models of resonant tunneling diodes

A satisfactory agreement between calculated voltage-current characteristics of GaAs/AlAs and Si/SiGe heterostructure resonant tunneling diodes and experimental data was obtained by using combined two-band models based on semiclassical and quantum-mechanical approaches. A high sensitivity of the characteristics of GaAs/AlAs-based devices to factors such as the transverse wave vector, changes of the heterostructure??s X-conduction band minimum, the surface charge density on heterointerfaces, and G-X intervalley scattering, is shown.     

纳米电子器件-高峰值峰谷电流比InP基共振隧穿二极管的实现

利用分子束外延技术研制出InP基IhAs/In0.53Ga0.47As/AlAs共振隧穿二极管,其中势垒为10个单分子AlAs,势阱由8个单分子层In0.53Ga0.47As阱和4个单分子层InAs子阱组成.室温下峰值电流密度接近3kA/cm2,峰和谷的电流密度比率达到19.     

Fabrication of 200-GHz fmax resonant-tunnelingdiodes for integration circuit and microwave applications

Room-temperature current densities of 1.3×10⁵ A/cm² and peak-to-valley ratios of 2.5 have been achieved for resonant tunneling diodes (RTDs) in the GaAs/AlAs material system. The devices were fabricated in a microwave-compatible process using topside contacts and a semi-insulating substrate to allow device integration. Proton implantation creates a nonconducting surface compatible with high-frequency coplanar transmission lines and other passive microwave structures     

A 50 GHz broad-band monolithic GaAs/AlAs resonant tunneling diodetrigger circuit

This paper describes the design, circuit simulation, fabrication and testing of a 50 GHz trigger circuit using GaAs/AlAs resonant tunneling diodes. A new trigger circuit was designed to eliminate the 180° phase splitter used in a previous complementary input trigger circuit. Our monolithic approach, integrated GaAs/AlAs resonant tunneling diodes (in a back-to-back configuration) and a 50 Ω coplanar waveguide, minimized the parasitic circuit elements and internal reflections from the package thus achieving high frequency operation. The circuit was able to trigger on input sinusoidal waves of input powers of -3 dBm up to 50 GHz with time jitter of less than 1 ps rms over the entire measured frequency range from 5 to 50 GHz. The upper limit of 50 GHz was imposed by our measurement system     

Influence of MBE growth temperature on GaAs/AlAs resonant tunneling structures

Double barrier GaAs/AlAs tunneling structures with typical 2.5:1 room temperature peak-to-valley current ratios are examined using Deep Level Transient Spectroscopy. Deep level trap concentrations are found to be much higher in samples grown at 550° C compared to those grown at 650° C. For devices grown at 550° C, an impedance switch-ing effect due to a high concentration of deep levels is observed. The peak-to-valley ratio of the tunneling devices is largely unaffected by the growth temperatures in this range, indicating that higher growth temperatures can be employed to grow resonant tunnel-ing diodes than previously suggested in the literature.     

新型电子器件和光学器件的共振隧穿结构

描述了一种新型共振隧穿结构器件，这种器件包含了通过可变间隙超晶格能量滤波器（ＶＳＳＥＦ）中的耦合量子附态的隧穿过程．论证了通过ＡｌＡｓ／ＧａＡｓＶＳＳＥＦ器件高能态和ＡｌＧａＡｓ／ＧａＡｓ超晶格受激态的共振隧穿，描述了这种器件作为较高功率微波源和共振隧穿晶体管的应用，并讨论了共振隧穿结构作为雪崩探测器和红外发射器等光学器件的潜在应用．