Similarity of electronic structure and optical properties of Mg ₂ NiH ₄ and Si

Abstract

Using the first-principles calculations a comparative analysis of electronic structure and optical properties of crystalline Si with cubic Mg 2 NiH4 and monoclinic Mg 2 NiH4 has been performed. It is found that the band structure of cubic Mg 2 NiH3 is similar to that of crystalline Si (c-Si), whereas the band gap of monoclinic Mg 2 NiH4 is similar to that of the hydrogenated amorphous Si (a-Si:H). It is shown that cubic Mg 2 NiH4 possesses the features of semiconductors such as wide fundamental band gap, capability for nand/or p-type electrical conductivity, and small carrier effective masses. It is concluded that Mg 2 NiH4 can be considered as a candidate, which is capable to replace c-Si and a-Si:H. It might be useful for the processing of electronic devices such as, e.g., solar cells at low temperatures. Advantages of using hydrides in semiconductor electronics are discussed.

Classification of hydrides according to features of band structure

“…Band structures of Mg 2 CoH 5 and SrAlSiH are similar to that of Ge. Such a similarity has been reported before for Si and Mg 2 NiH 4 [7]. (Table I).…”

“…Recently, novel application of hydrides has been suggested in semiconductor electronics [5,6], photovoltaics [7] and optoelectronics [8]. For these applications weight percent of hydrogen in the compound, fast kinetics of hydrogen absorption and desorption are not preferable.…”

“…It is necessary to note also that some hydrides with an open band gap are found to conduct 3 electrical current [9,11,12]. It has to be mentioned also that after the invention of "hydride electronics" [7], comparative analysis of electronic structure and optical properties of hydrides and semiconductors has been performed [4][5][6]. In particular it is found [8], that electronic structure and optical properties of cubic and monoclinic modifications of Mg 2 NiH 4 are similar to that of crystalline and hydrogenated amorphous Si, respectively.…”

MgyNi1−y(Hx) thin films deposited by magnetron co-sputtering

“…MgH 2 and Mg 2 NiH 4 stores respectively 7.6 wt% and 3.6 wt% hydrogen [1]. Also several other applications have been proposed, involving thin films of Mg-Ni-H for use in smart windows [2], hydrogen sensors [3], semiconductor electronics [4], solar cells [5] and data storage [6]. These applications rely on the respectively insulating and semiconducting nature of the hydrides of Mg and Mg 2 Ni.…”

Structural, electronic, optical and elastic properties of the complex K2PtCl6-structure hydridesARuH6(A= Mg, Ca, Sr and Ba): first-principles study

“…However, the high stabilities and high hydrogen density of these hydrides make them potentially attractive for high-temperature applications, such as the thermochemical storage of heat for solar thermal plants or excess industrial heat for which hydrogen discharge temperature exceeding 700 K are desired [23,31,32]. On other hand, the high temperature stabilities and semiconducting character of some of these materials led the researchers to the idea that these hydrides can be useful in semiconductor electronics [33,34], photovoltaics [35] and optoelectronic devices [36]. The requested hydrides for the above-mentioned novel applications should be air-and moisture-stable; their kinetics of hydrogenation/dehydrogenation processes should be as slow as possible; they should have open fundamental band gaps and be capable of conducting electrical current [29].…”