We report a detailed investigation of resistance noise in single layer graphene films on Si/SiO$_2$ substrates obtained by chemical vapor deposition (CVD) on copper foils. We find that noise in these systems to be rather large, and when expressed in the form of phenomenological Hooge equation, it corresponds to Hooge parameter as large as $0.1 - 0.5$. We also find the variation in the noise magnitude with the gate voltage (or carrier density) and temperature to be surprisingly weak, which is also unlike the behavior of noise in other forms of graphene, in particular those from exfoliation.
Tight-binding terahertz plasmons in chemical vapor deposited graphene
包括石墨烯和亚波长金属光栅的晶体管结构对于等离子体激元增强的太赫兹检测具有很大的希望。尽管有相当多的理论研究，但到目前为止，在这种结构中几乎没有发现太赫兹等离子体激元的实验证据。在这里，我们报告了在石墨烯绝缘体光栅结构中使用傅里叶变换光谱在5-10太赫兹范围内的等离子体激元的实验研究。即使在具有低载流子迁移率$\sim 10^3$ cm $^2$ /（Vs）的化学气相沉积（CVD）石墨烯中，等离子体共振在Drude吸收背景之上也是清晰可见的。我们认为，等离子体激元寿命是弱敏感的散射晶界和宏观缺陷，限制了CVD样品的流动性。在将光栅放置在石墨烯附近时，等离子体激元场变得紧密地束缚在金属条下方，而谐振频率由条宽度而不是光栅周期确定。我们的研究结果打开了大面积商用石墨烯共振太赫兹探测器的前景。
Electronic Transport in Chemical Vapor Deposited Graphene Synthesized on Cu: Quantum Hall Effect and Weak Localization
我们报告的电子性质的石墨烯合成的化学气相沉积（CVD）铜，然后转移到SiO2/Si。已经合成了晶圆级（高达4英寸）石墨烯膜，如光谱拉曼映射所示，主要由单层石墨烯组成。在由这种CVD石墨烯制造的微型器件上进行低温输运测量，显示双极场效应（开/关比约为5，载流子迁移率高达约3000 cm ^2/Vs）和“半整数”量子霍尔效应，这是单层石墨烯的固有电子性质的标志。我们还观察到弱本地化和提取信息的相位相干性和散射的载波。
Self-Assembled Nanostructure Formation in Chemical Vapor Deposition
当通过化学气相沉积在衬底上生长薄膜时，第一沉积层的演变可以在介观尺度上通过反应扩散型动力学模型来描述。对于单原子层，这样的模型描述的原子覆盖的演变，由于代表吸附-脱附和化学过程和非线性扩散项的Cahn-Hilliard型的反应项的组合效应。在低于临界温度时，这种组合可能导致均匀沉积层的不稳定性。这种不稳定性触发了对应于基底覆盖的规则空间变化的纳米结构的形成。模式、波长和对称性是由动力学变量而不是变分变元选择的。根据反应和扩散诱导的非线性之间的平衡，可以获得一系列的自组装结构，包括六边形阵列的点，条和各种类型的局部结构。这些结构可以启动不同类型的生长机制，包括Volmer-Weber和Frank-Van der Merwe类型的生长。不同类型的沉积单层的研究，这种方法的相关性进行了讨论。
The expected high performance of graphene-based electronics is often hindered by lack of adequate doping, which causes low carrier density and large sheet resistance. Many reported graphene doping schemes also suffer from instability or incompatibility with existing semiconductor processing. Here we report ultrahigh and stable p-type doping up to ~7x10^13 1/cm^2 (~2x10^21 1/cm^3}) of monolayer graphene grown by chemical vapor deposition. This is achieved by direct polycrystalline MoO3 growth on graphene using a rapid flame synthesis technique. With this approach, the metal-graphene contact res…
Our study shows that deposited Ge and Si dielectric thin-films can exhibit low microwave losses at near single-photon powers and sub-Kelvin temperatures ($\approx$40 mK). This low loss enables their use in a wide range of devices, including low-loss coplanar, microstrip, and stripline resonators, as well as layers for device isolation, inter-wiring dielectrics, and passivation in microwave and Josephson junction circuit fabrication. We use coplanar microwave resonator structures with narrow trace widths of 2-16 $μ\textrm{m}$ to maximize the sensitivity of loss tangent measurements to the inter…
We fabricate an undoped Ge quantum well under 30 nm Ge0.8Si0.2 shallow barrier with reverse grading technology. The under barrier is deposited by Ge0.8Si0.2 followed by Ge0.9Si0.1 so that the variation of Ge content forms a sharp interface which can suppress the threading dislocation density penetrating into undoped Ge quantum well. And the Ge0.8Si0.2 barrier introduces enough in-plane parallel strain -0.41% in the Ge quantum well. The heterostructure field-effect transistors with a shallow buried channel get a high two-dimensional hole gas (2DHG) mobility over 2E6 cm2/Vs at a low percolation …
