Stability and electronic structures of isoelectronic impurity complexes in Si: First-principles study

Abstract

The stability and electronic structures of various isoelectronic cation+anion pairs in Si were studied by first-principles calculations. It was shown that the nearest-neighboring substitutional configuration is the most stable structure for most cation+anion pairs, while B+N, Mg+O, and Be+O pairs preferentially occupy a single Si site owing to the small atomic radii of B, N, and O atoms. We found that only Al+N, Ga+N, and In+N pairs produce electron-unoccupied weakly localized states in the band gap of Si, reflecting the large negativity of N atoms. We also showed that single N doping produces N+N pairs and that such pairs induce no electronic states in the band gap of Si. Therefore, the codoping of Al and N atoms is essential to produce an electronic state in the Si band gap and increase the tunneling current in Si tunneling field-effect transistors.

Process and device integration for silicon tunnel FETs utilizing isoelectronic trap technology to enhance the ON current

“…34) They showed that the nearest-neighbor configuration for which both Al and N are substitutional at Si sites is the most stable among a considerable number of configurations, including interstitials. 35) This structure follows the experimental prediction.…”

Enhancement of tunneling currents by isoelectronic nitrogen-atom doping at semiconductor pn junctions; comparison of indirect and direct band-gap systems

“…[15][16][17][18][19][20][21] In order to clarify the electronic structures of such codoping systems, our group showed by the first-principles calculation that Al and N atoms produce a nearest-neighboring pair in Si layers and produce an electron-unoccupied isoelectronic impurity state below the conduction-band of Si. [22][23][24] In addition, by using the one-dimensional model and wave-packet simulation, 25,26) we showed that such an impurity state becomes the resonance state with conductionband states of n-Si layers when the Al-N pair is located in Si-pn junction under the electric field, shortens the tunneling length between p-and n-Si layers as a stepping stone, and markedly increases the tunneling current, which well explains the experiments. However, this study is the case of a onedimensional model system.…”

“…© 2022 The Japan Society of Applied Physics n m of host bulk semiconductors of Si, Ge, GaP, InP, and GaAs are taken from previous literatures. [28][29][30][31][32] As isoelectronic N-atom dopants, we consider an Al-N nearest-neighboring pair in Si and Ge, [15][16][17][18][19][20][21][22][23][24] and an isolated N atom in GaP, InP, and GaAs. We assume that these impurity atoms are substitutionally located at atomic sites of host semiconductors, especially at anion site in GaP, InP, and GaAs.…”

Material engineering for silicon tunnel field-effect transistors: isoelectronic trap technology

“…[70] The most recent studies were conducted by Iizuka and Nakayama using first-principles calculations. [73,74] They clarified the stable atomic configuration of the Al-N pair: the substitutional nearest-neighbor configuration is preferred over configurations comprising interstitials [ Fig. 3(b)].…”