Control of Electron and Hole Concentrations in Semiconducting Silicide BaSi₂with Impurities Grown by Molecular Beam Epitaxy

Abstract

Highly a-axis-oriented n- and p-type BaSi2 films were grown on Si(111) substrates by molecular beam epitaxy using Sb and In doping atoms, respectively. The hole concentration of In-doped BaSi2 was controlled in the range between 1016 and 1017 cm-3 at room temperature by changing the temperature of the In Knudsen cell crucible. In contrast, the electron concentration of Sb-doped BaSi2 was controlled in the range between 1016 and 1020 cm-3 by the substrate temperature. The electron and hole mobilities decreased with increasing electron and hole density, respectively.

Potential variations around grain boundaries in impurity-doped BaSi2 epitaxial films evaluated by Kelvin probe force microscopy

“…The details of the growth procedure were already reported. 35,38 An ion-pumped MBE system equipped with standard Knudsen cells for Ba, Sb, and B, and an electron-beam evaporation source for Si was used. We adopted the growth condition so that the hole concentration, p, in the B-doped BaSi 2 becomes much higher than the electron concentration, n, in the Sb-doped BaSi 2 .…”

“…33,34 Impurity doping of group-III and group-V elements enables us to control the carrier type and conductivity of BaSi 2 experimentally. [35][36][37][38][39] Among them, boron (B) and antimony (Sb) atoms are considered suitable for p-and n-type dopants, respectively, because the carrier concentration can be controlled in a wide range between 10 17 and 10 20 cm À3 at room temperature (RT). 35,38 This article reports on the surface potential variations around the GBs in Sb-doped n-BaSi 2 and B-doped p-BaSi 2 films, and discusses their dependence on carrier concentrations.…”

“…[35][36][37][38][39] Among them, boron (B) and antimony (Sb) atoms are considered suitable for p-and n-type dopants, respectively, because the carrier concentration can be controlled in a wide range between 10 17 and 10 20 cm À3 at room temperature (RT). 35,38 This article reports on the surface potential variations around the GBs in Sb-doped n-BaSi 2 and B-doped p-BaSi 2 films, and discusses their dependence on carrier concentrations. We also discussed their densities of states (DOSs) and total energies using first-principles pseudopotential method to clarify the possible insertion sites of impurity atoms, and the reason for the observed n-type conduction in Sb-doped BaSi 2 and p-type conduction in B-doped BaSi 2 40 and found that the In (Ga)-doped BaSi 2 was expected to be p-type, and that substitution of Si in the BaSi 2 lattice by In (Ga) is more favorable than that of Ba from the energetic point of view.…”

Improved photoresponsivity of semiconducting BaSi2 epitaxial films grown on a tunnel junction for thin-film solar cells

“…An approximately 25 nm thick Sb-doped n þ -BaSi 2 layer was grown by MBE at 490 C on a heavily boron doped p þ /pSi substrate (N A $ 3 Â 10 19 cm À3 ). 18,24 A 10 nm thick amorphous Si (a-Si) layer was then deposited onto the n þ -BaSi 2 layer at room temperature (RT), followed by annealing at 650 C for 1 min to transform the a-Si into crystalline Si by SPE. The c-Si layer was changed into BaSi 2 by Ba deposition at 520 C. Finally, an approximately 400 nm thick undoped BaSi 2 layer was grown by MBE at 490 C (sample A).…”

Possibility of Si-based new material for thin-film solar cell applications

“…According to Imai and Watanabe [9], substitution of Si in the BaSi 2 lattice is more favorable than substitution of Ba from an energetic point of view by firstprinciples calculation. In our previous works, the electron concentration of Sb-doped n-type BaSi 2 was controlled in the range between 10 16 and 10 20 cm -3 at room temperature (RT) [10]. Very recently, we have achieved the hole concentration exceeding 10 19 cm -3 in B-doped p-type BaSi 2 .…”