Configuration- and concentration-dependent electronic properties of hydrogenated graphene

Abstract

The electronic properties of hydrogenated graphenes are investigated with the first-principles calculations. Geometric structures, energy bands, charge distributions, and density of states (DOS) strongly depend on the different configurations and concentrations of hydrogen adatoms. Among three types of optimized periodical configurations, only in the zigzag systems the band gaps can be remarkably modulated by H-concentrations. There exist middle-gap semiconductors, narrow-gap semiconductors, and gapless systems. The band structures exhibit the rich features, including the destruction or recovery of the Dirac-cone structure, newly formed critical points, weakly dispersive bands, and (C,H)-related partially flat bands. The orbitalprojected DOS are evidenced by the low-energy prominent peaks, delta-function-like peaks, discontinuous shoulders, and logarithmically divergent peaks. The DOS and spatial charge distributions clearly indicate that the critical bondings in C-C and C-H is responsible for the diversified properties.

Diverse Quantization Phenomena in Layered Materials

“…This differential power is accurately measured and recorded. Very interesting, an extension of DSC, a modulated differential scanning calorimeter [72,73], is further developed to provide the more reliable [77,80] and lattice specific heat [?]. The previous experiments clearly show that the former presents a linear T-dependence at very low temperature [T < 1.2 K; [77]], and the latter follows the T 3 law at low temperature and approximately T 2 law at higher temperature [78].…”

“…Very interesting, an extension of DSC, a modulated differential scanning calorimeter [72,73], is further developed to provide the more reliable [77,80] and lattice specific heat [?]. The previous experiments clearly show that the former presents a linear T-dependence at very low temperature [T < 1.2 K; [77]], and the latter follows the T 3 law at low temperature and approximately T 2 law at higher temperature [78]. The applications of graphite systems promise an economical way to a new class of efficient thermal management materials, such as, the relatively high thermal conductivities very suitable for thermal interface applications [81,82].…”

“…The diverse physical phenomena, including the semiconductors, semimetals and metals the absence or recovery of the Dirac-cone structures [73], the linear, parabolic and oscillatory energy dispersions [74], the critical points in the energy-wave-vector space [the minima, maxima and saddle points; Ref. [36]], the semiconductor-metal transition [75,76], the creation of band gap [77], and non-magnetic, ferromagnetic or anti-ferromagnetic spin configurations [78], are clearly explained by the concise physical and chemical pictures. The close associations of the firstprinciples calculations and the generalized tight-binding model will be very useful for the emergent 2D materials in exploring the various magnetic quantization phenomena.…”

“…It is well known that the geometric symmetries are one of the critical factors in determining the fundamental physical, chemical and material properties. The condensed-matter sys-tems, which are purely made up of carbon atoms, include the significant sp 3 [73,74,75,76], sp 2 [73,75,76], and sp chemical bondings [73,77], being, respectively, revealed as the 3D bulk, 2D surface, and 1D line structures, such as, diamond, graphene and carbon chain. Apparently, the diversified orbital hybridizations in C-C bonds originate from the four half occupied orbitals of [2s, 2p x , 2p y , 2p z ].…”

Влияние Дегидрирования Графана На Его Механические И Электронные Свойства

“…Для электронных приложений частично дегидриро-ванного графана представляют интерес результаты ра-боты [21]. В этой работе показано, что в зависимости от конфигурации и концентрации периодически располо-женных атомов водорода запрещенная зона может иметь различную ширину или вовсе отсутствовать.…”