اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدPhoto-Thermoelectric Effect at a Graphene Interface Junction
89
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We investigate the optoelectronic response of a graphene interface junction, formed with bilayer and single-layer graphene, by photocurrent (PC) microscopy. We measure the polarity and amplitude of the PC while varying the Fermi level by tuning a gate voltage. These measurements show that the generation of PC is by a photo-thermoelectric effect. The PC displays a factor of ~10 increase at the cryogenic temperature as compared to room temperature. Assuming the thermoelectric power has a linear dependence on the temperature, the inferred graphene thermal conductivity from temperature dependent measurements has a T^{1.5} dependence below ~100 K, which agrees with recent theoretical predictions.
قيم البحث
اقرأ أيضاً
We report on the fabrication and transport studies of a single-layer graphene p-n junction. Carrier type and density in two adjacent regions are individually controlled by electrostatic gating using a local top gate and a global back gate. A function
alized Al203 oxide that adheres to graphene and does not significantly affect its electronic properties is described. Measurements in the quantum Hall regime reveal new plateaus of two-terminal conductance across the junction at 1 and 3/2 times the quantum of conductance, e2/h, consistent with theory.
We have tuned in situ the proximity effect in a single graphene layer coupled to two Pt/Ta superconducting electrodes. An annealing current through the device changed the transmission coefficient of the electrode/graphene interface, increasing the pr
obability of multiple Andreev reflections. Repeated annealing steps improved the contact sufficiently for a Josephson current to be induced in graphene.
Graphenes high mobility and Fermi velocity, combined with its constant light absorption in the visible to far-infrared range, make it an ideal material to fabricate high-speed and ultra-broadband photodetectors. However, the precise mechanism of phot
odetection is still debated. Here, we report wavelength and polarization dependent measurements of metal-graphene-metal photodetectors. This allows us to quantify and control the relative contributions of both photo-thermo- and photoelectric effects, both contributing to the overall photoresponse. This paves the way for a more efficient photodetector design for ultra-fast operating speeds.
The thermoelectric response of high mobility single layer epitaxial graphene on silicon carbide substrates as a function of temperature and magnetic field have been investigated. For the temperature dependence of the thermopower, a strong deviation f
rom the Mott relation has been observed even when the carrier density is high, which reflects the importance of the screening effect. In the quantum Hall regime, the amplitude of the thermopower peaks is lower than a quantum value predicted by theories, despite the high mobility of the sample. A systematic reduction of the amplitude with decreasing temperature suggests that the suppression of the thermopower is intrinsic to Dirac electrons in graphene.
An interface electron state at the junction between a three-dimensional topological insulator (TI) film of Bi2Se3 and a ferrimagnetic insulator film of Y3Fe5O12 (YIG) was investigated by measurements of angle-resolved photoelectron spectroscopy and X
-ray absorption magnetic circular dichroism (XMCD). The surface state of the Bi2Se3 film was directly observed and localized 3d spin states of the Fe3+ state in the YIG film were confirmed. The proximity effect is likely described in terms of the exchange interaction between the localized Fe 3d electrons in the YIG film and delocalized electrons of the surface and bulk states in the Bi2Se3 film. The Curie temperature (TC) may be increased by reducing the amount of the interface Fe2+ ions with opposite spin direction observable as a pre-edge in the XMCD spectra.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
