اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدHigh-Yield of Memory Elements from Carbon Nanotube Field-Effect Transistors with Atomic Layer Deposited Gate Dielectric
251
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Carbon nanotube field-effect transistors (CNT FETs) have been proposed as possible building blocks for future nano-electronics. But a challenge with CNT FETs is that they appear to randomly display varying amounts of hysteresis in their transfer characteristics. The hysteresis is often attributed to charge trapping in the dielectric layer between the nanotube and the gate. This study includes 94 CNT FET samples, providing an unprecedented basis for statistics on the hysteresis seen in five different CNT-gate configurations. We find that the memory effect can be controlled by carefully designing the gate dielectric in nm-thin layers. By using atomic layer depositions (ALD) of HfO$_{2}$ and TiO$_{2}$ in a triple-layer configuration, we achieve the first CNT FETs with consistent and narrowly distributed memory effects in their transfer characteristics.
قيم البحث
اقرأ أيضاً
We report magnetotransport measurements of a gated InSb quantum well (QW) with high quality Al2O3 dielectrics (40 nm thick) grown by atomic layer deposition. The magnetoresistance data demonstrate a parallel conduction channel in the sample at zero g
ate voltage (Vg). A good interface between Al2O3 and the top InSb layer ensures that the parallel channel is depleted at negative Vg and the density of two-dimensional electrons in the QW is tuned by Vg with a large ratio of 6.5x1014 m-2V-1 but saturates at large negative Vg. These findings are closely related to layer structures of the QW as suggested by self-consistent Schrodinger-Poisson simulation and two-carrier model.
Diamond has attracted attention as a next-generation semiconductor because of its various exceptional properties such as a wide bandgap and high breakdown electric field. Diamond field effect transistors, for example, have been extensively investigat
ed for high-power and high-frequency electronic applications. The quality of their charge transport (i.e., mobility), however, has been limited due to charged impurities near the diamond surface. Here, we fabricate diamond field effect transistors by using a monocrystalline hexagonal boron nitride as a gate dielectric. The resulting high mobility of charge carriers allows us to observe quantum oscillations in both the longitudinal and Hall resistivities. The oscillations provide important information on the fundamental properties of the charge carriers, such as effective mass, lifetime, and dimensionality. Our results indicate the presence of a high-quality two-dimensional hole gas at the diamond surface and thus pave the way for studies of quantum transport in diamond and the development of low-loss and high-speed devices.
The observed performances of carbon nanotube field effect transistors are examined using first-principles quantum transport calculations. We focus on the nature and role of the electrical contact of Au and Pd electrodes to open-ended semiconducting n
anotubes, allowing the chemical contact at the surface to fully develop through large-scale relaxation of the contacting atomic configuration. We present the first direct numerical evidence of Pd contacts exhibiting perfect transparency for hole injection as opposed to that of Au contacts. Their respective Schottky barrier heights, on the other hand, turn out to be fairly similar for realistic contact models. These findings are in general agreement with experimental data reported to date, and show that a Schottky contact is not merely a passive ohmic contact but actively influences the device I-V behavior.
Metal-oxide-semiconductor field-effect transistors (MOSFETs) using atomic-layer-deposited (ALD) Al$_2$O$_3$ as the gate dielectric are fabricated on the Si/Si$_{1-x}$Ge$_x$ heterostructures. The low-temperature carrier density of a two-dimensional el
ectron system (2DES) in the strained Si quantum well can be controllably tuned from 2.5$times10^{11}$cm$^{-2}$ to 4.5$times10^{11}$cm$^{-2}$, virtually without any gate leakage current. Magnetotransport data show the homogeneous depletion of 2DES under gate biases. The characteristic of vertical modulation using ALD dielectric is shown to be better than that using Schottky barrier or the SiO$_2$ dielectric formed by plasma-enhanced chemical-vapor-deposition(PECVD).
While decreasing the oxide thickness in carbon nanotube field-effect transistors (CNFETs) improves the turn-on behavior, we demonstrate that this also requires scaling the range of the drain voltage. This scaling is needed to avoid an exponential inc
rease in Off-current with drain voltage, due to modulation of the Schottky barriers at both the source and drain contact. We illustrate this with results for bottom-gated ambipolar CNFETs with oxides of 2 and 5 nm, and give an explicit scaling rule for the drain voltage. Above the drain voltage limit, the Off-current becomes large and has equal electron and hole contributions. This allows the recently reported light emission from appropriately biased CNFETs.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
