اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدContactless photoconductivity measurements on (Si) nanowires
135
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Conducting nanowires possess remarkable physical properties unattainable in bulk materials. However our understanding of their transport properties is limited by the difficulty of connecting them electrically. In this Letter we investigate phototransport in both bulk silicon and silicon nanowires using a superconducting multimode resonator operating at frequencies between 0.3 and 3 GHz. We find that whereas the bulk Si response is mainly dissipative, the nanowires exhibit a large dielectric polarizability. This technique is contactless and can be applied to many other semiconducting nanowires and molecules. Our approach also allows to investigate the coupling of electron transport to surface acoustic waves in bulk Si and to electro-mechanical resonances in the nanowires.
قيم البحث
اقرأ أيضاً
We analyze the strain state of GaN nanowire ensembles by x-ray diffraction. The nanowires are grown by molecular beam epitaxy on a Si(111) substrate in a self-organized manner. On a macroscopic scale, the nanowires are found to be free of strain. How
ever, coalescence of the nanowires results in micro-strain with a magnitude from +-0.015% to +-0.03%.This micro-strain contributes to the linewidth observed in low-temperature photoluminescence spectra.
General expressions for the electron- and hole-acoustical-phonon deformation potential Hamiltonian (H_{E-DP}) are derived for the case of Ge/Si and Si/Ge core/shell nanowire structures (NWs) with circular cross section. Based on the short-range elast
ic continuum approach and on derived analytical results, the spatial confined effects on the vector phonon displacement, the phonon dispersion relation and the electron- and hole-phonon scattering amplitudes are analyzed. It is shown that the acoustical vector displacement, phonon frequencies and H_{E-DP} present mixed torsional, axial, and radial components depending on the angular momentum quantum number and phonon wavector under consideration. The treatment shows that bulk group velocities of the constituent materials are renormalized due to the spatial confinement and intrinsic strain at the interface. The role of insulating shell on the phonon dispersion and electron-phonon coupling in Ge/Si and Si/Ge NWs are discussed.
Recently, two-dimensional materials and in particular transition metal dichalcogenides (TMDs) were extensively studied because of their strong light-matter interaction and the remarkable optoelectronic response of their field-effect transistors (FETs
). Here, we report a photoconductivity study from FETs built from few-layers of p-WSe2 measured in a multi-terminal configuration under illumination by a 532 nm laser source. The photogenerated current was measured as a function of the incident optical power, of the drain-to-source bias and of the gate voltage. We observe a considerably larger photoconductivity when the phototransistors were measured via a four-terminal configuration when compared to a two-terminal one. For an incident laser power of 248 nW, we extract 18 A/W and ~4000% for the two-terminal responsivity (R) and the concomitant external quantum efficiency (EQE) respectively, when a bias voltage Vds = 1 V and a gate voltage Vbg = 10 V are applied to the sample. R and EQE are observed to increase by 370% to ~85 A/W and ~20000% respectively, when using a four-terminal configuration. Thus, we conclude that previous reports have severely underestimated the optoelectronic response of transition metal dichalcogenides, which in fact reveals a remarkable potential for photosensing applications.
We settle a general expression for the Hamiltonian of the electron-phonon deformation potential (DP) interaction in the case of non-polar core-shell cylindrical nanowires (NWs). On the basis of long range phenomenological continuum model for the opti
cal modes and by taking into account the bulk phonon dispersions, we study the size dependence and strain-induced shift of the electron-phonon coupling strengths for Ge-Si and Si-Ge NWs. We derive analytically the DP electron-phonon Hamiltonian and report some numerical results for the frequency core modes and vibrational amplitudes. Our approach allows for the unambiguous identification of the strain and confinement effects. We explore the dependence of mode frequencies and hole-DP scattering rates on the structural parameters of these core-shell structures, which constitute a basic tool for the characterization and device applications of these novel nanosystems.
Inspired by recent experimental realizations and theoretical simulations of thin silicon nanowire-based devices, we perform predictive first-principles simulations of junctionless gated Si nanowire transistors. Our primary predictions are that Si-bas
ed transistors are physically possible without major changes in design philosophy at scales of ~1 nm wire diameter and ~3 nm gate length, and that the junctionless transistor may be the only physically sensible design at these length scales. We also present investigations into atomic-level design factors such as dopant positioning and concentration.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
