اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThickness Dependent Parasitic Channel Formation at AlN/Si Interfaces
69
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The performance of GaN-on-Silicon electronic devices is severely degraded by the presence of a parasitic conduction pathway at the nitride-substrate interface which contributes to switching losses and lower breakdown voltages. The physical nature of such a parasitic channel and its properties are however, not well understood. We report on a pronounced thickness dependence of the parasitic channel formation at AlN/Si interfaces due to increased surface acceptor densities at the interface in silicon. The origin of these surface acceptors is analyzed using secondary ion mass spectroscopy measurements and traced to thermal acceptor formation due to Si-O-N complexes. Low-temperature (5K) magneto-resistance (MR) data reveals a transition from positive to negative MR with increasing AlN film thickness indicating the presence of an inversion layer of electrons which also contributes to parasitic channel formation but whose contribution is secondary at room temperatures.
قيم البحث
اقرأ أيضاً
The critical thickness constitutes a vital parameter in heterostructure epitaxy engineering as it determines the limit where crystal coherency is lost. By finite element modeling of the total strain relaxation in finite size heterostructure nanowires
, we show that the equilibrium configuration changes abruptly at the critical thickness from a fully elastically strained structure to a structure with a network of MDs. We show how the interdependent MD relaxation changes as a function of the lattice mismatch. These findings suggest that a collective formation of MDs takes place when the growing heterostructure layer exceeds the critical thickness.
This article addresses the much debated question whether the degree of hydrophobicity of single-layer graphene (1LG) is different from the one of double-layer graphene (2LG). Knowledge of the water affinity of graphene and its spatial variations is c
ritically important as it can affect the graphene properties as well as the performance of graphene devices exposed to humidity. By employing chemical force microscopy (CFM) with a probe rendered hydrophobic by functionalization with octadecyltrichlorosilane (OTS), the adhesion force between the probe and epitaxial graphene on SiC has been measured in deionized water. Owing to the hydrophobic attraction, a larger adhesion force was measured on 2LG domains of graphene surfaces, thus showing that 2LG is more hydrophobic than 1LG. Identification of 1LG and 2LG domains was achieved through Kelvin probe force microscopy and Raman spectral mapping. Approximate values of the adhesion force per OTS molecule have been calculated through contact area analysis. Furthermore, the contrast of friction force images measured in contact mode was reversed to the 1LG/2LG adhesion contrast and its origin was discussed in terms of the likely water depletion over hydrophobic domains as well as deformation in the contact area between AFM tip and 1LG.
The barrier formation for metal/organic semiconductor interfaces is analyzed within the Induced Density of Interface States (IDIS) model. Using weak chemisorption theory, we calculate the induced density of states in the organic energy gap and show t
hat it is high enough to control the barrier formation. We calculate the Charge Neutrality Levels of several organic molecules (PTCDA, PTCBI and CBP) and the interface Fermi level for their contact with a Au(111) surface. We find an excellent agreement with the experimental evidence and conclude that the barrier formation is due to the charge transfer between the metal and the states induced in the organic energy gap.
To develop silicon-based spintronic devices, we have explored high-quality ferromagnetic Fe$_{3}$Si/silicon (Si) structures. Using low-temperature molecular beam epitaxy at 130 $^circ$C, we realize epitaxial growth of ferromagnetic Fe$_{3}$Si layers
on Si (111) with keeping an abrupt interface, and the grown Fe$_{3}$Si layer has the ordered $DO_{3}$ phase. Measurements of magnetic and electrical properties for the Fe$_{3}$Si/Si(111) yield a magnetic moment of ~ 3.16 $mu_{B}$/f.u. at room temperature and a rectifying Schottky-diode behavior with the ideality factor of ~ 1.08, respectively.
Domain walls are of increasing interest in ferroelectrics because of their unique properties and potential applications in future nanoelectronics. However, the thickness of ferroelastic domain walls remains elusive due to the challenges in experiment
al characterization. Here, we determine the atomic structure of ferroelastic domain walls and precisely measure the polarization and domain wall thickness at picometer scale using annular bright field imaging in an aberration-corrected scanning transmission electron microscope. We find that the domain wall thickness in PbZr0.2Ti0.8O3 and PbTiO3 thin films is typically about one-unit cell, across which the oxygen octahedron distortion behavior is in excellent agreement with first principles calculations. Remarkably, wider domain walls about two-unit cells in thickness are also observed for those domains walls are coupled with dislocations and underwent a compressive strain. These results suggest that the thickness of ferroelastic domain walls highly depends on their atomic environments. This study can help us to understand the past debatable experimental results and provide further insights into control of domain walls via strain engineering for their possible applications in nanoelectronics.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
