اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدSemiconducting character of LaN: magnitude of the band gap, and origin of the electrical conductivity
103
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Lanthanum nitride (LaN) has attracted research interest in catalysis due to its ability to activate the triple bonds of N$_2$ molecules, enabling efficient and cost-effective synthesis of ammonia from N$_2$ gas. While exciting progress has been made to use LaN in functional applications, the electronic character of LaN (metallic, semi-metallic, or semiconducting) and magnitude of its band gap have so far not been conclusively determined. Here, we investigate the electronic properties of LaN with hybrid density functional theory calculations. In contrast to previous claims that LaN is semi-metallic, our calculations show that LaN is a direct-band-gap semiconductor with a band-gap value of 0.62 eV at the X point of the Brillouin zone. The dispersive character of the bands near the band edges leads to light electron and hole effective masses, making LaN promising for electronic and optoelectronic applications. Our calculations also reveal that nitrogen vacancies and substitutional oxygen atoms are two unintentional shallow donors with low formation energies that can explain the origin of the previously reported electrical conductivity. Our calculations clarify the semiconducting nature of LaN and reveal candidate unintentional point defects that are likely responsible for its measured electrical conductivity.
قيم البحث
اقرأ أيضاً
The thermal conductivity of the iron-based superconductor FeSe was measured at temperatures down to 50 mK in magnetic fields up to 17 T. In zero magnetic field, the electronic residual linear term in the T = 0 limit, kappa_0/T, is vanishingly small.
Application of a magnetic field H causes no increase in kappa_0/T initially. Those two observations show that there are no zero-energy quasiparticles that carry heat and therefore no nodes in the superconducting gap of FeSe. The full field dependence of kappa_0/T has the classic shape of a two-band superconductor, such as MgB2: it rises exponentially at very low field, with a characteristic field H* << Hc2, and then more slowly up to the upper critical field Hc2. This shows that the superconducting gap is very small on one of the pockets in the Fermi surface of FeSe.
Here we report two-dimensional (2D) single-crystalline holey-graphyne (HGY) created an interfacial two-solvent system through a Castro-Stephens coupling reaction from 1,3,5-tribromo-2,4,6-triethynylbenzene. HGY is a new type of 2D carbon allotrope wh
ose structure is comprised of a pattern of six-vertex and eight-vertex rings. The carbon-carbon 2D network of HGY is alternately linked between benzene rings and sp (carbon-carbon triple bond) bonding. The ratio of the sp over sp2 bonding is 50%. It is confirmed that HGY is stable by DFT calculation. The vibrational, optic, and electric properties of HGY are investigated theoretically and experimentally. It is a p-type semiconductor that embraces a natural direct band gap (~ 1.0 eV) with high hole mobility and electron mobility at room temperature. This report is expected to help develop a new types of carbon-based semiconductor devices with high mobility.
We study the size dependence of thermal conductivity in nanoscale semiconducting systems. An analytical formula including the surface scattering and the size confinement effects of phonon transport is derived. The theoretical formula gives good agree
ments with the existing experimental data for Si and GaAs nanowires and thin films.
Motivated by the recent successful formation of the MoSi2N4 monolayer [Hong et al., Sci. 369, 670 (2020)], the structural, electronic and magnetic properties of MoSi2N4 nanoribbons (NRs) is investigated for the first time . The band structure calcula
tions showed spin-polarization in zigzag edges and a non-magnetic semiconducting character in armchair edges. For armchair-edges, we identify an indirect to direct band gap shift compared to the MoSi2N4 monolayer, and its energy gap increases with increasing NR width. Anisotropic electrical and magnetic behavior is observed via band structure calculations in the zigzag and armchair edges, where, surprisingly, for the one type of zigzag-edges configuration, we identify a Dirac-semimetal character. The appearance of magnetism and Dirac-semimetal in MoSi2N4 ribbon can give rise to novel physical properties, which could be useful in applications for next-generation electronic devices.
Understanding the nature of the interaction at the graphene/metal interfaces is the basis for graphene-based electron- and spin-transport devices. Here we investigate the hybridization between graphene- and metal-derived electronic states by studying
the changes induced through intercalation of a pseudomorphic monolayer of Cu in between graphene and Ir(111), using scanning tunnelling microscopy and photoelectron spectroscopy in combination with density functional theory calculations. We observe the modifications in the band structure by the intercalation process and its concomitant changes in the charge distribution at the interface. Through a state-selective analysis of band hybridization, we are able to determine their contributions to the valence band of graphene giving rise to the gap opening. Our methodology reveals the mechanisms that are responsible for the modification of the electronic structure of graphene at the Dirac point, and permits to predict the electronic structure of other graphene-metal interfaces.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
