Fabrication of As-doped n-type BaSi₂ epitaxial films grown by molecular beam epitaxy

Abstract

We grow As-doped BaSi2 epitaxial films by molecular beam epitaxy (MBE) with GaAs granules as an As source and investigated their electrical and optical properties by changing a substrate temperature (TS) and a crucible temperature of GaAs (TGaAs) during MBE. Secondary ion mass spectrometry revealed that the density of As atoms in BaSi2 films was surely changed by TGaAs.The full width at half-maximum evaluated by the x-ray ω-scan rocking curve measurement reached a minimum of 0.36 ° at TS = 600 °C. We investigated the TS dependence of electron concentration (n) and mobility by Hall measurement. n increased with decreasing TS and reached a maximum of 4.3 × 10 18 cm −3 . The photoresponsivity of the As-doped BaSi2 films was higher than that of undoped ones at the same bias voltage, probably thanks to the reduction of point defects by As doping.

Significant enhancement of photoresponsivity in As-doped n-BaSi2epitaxial films by atomic hydrogen passivation

“…We set the temperature of GaAs granules at 300 °C, because the photoresnponsivity of As-doped BaSi2 films reached a maximum at around this temperature. 32) The As concentration (NAs) in the As-doped BaSi2 films was below the limit of detection by secondary ion mass spectrometry (SIMS) (NAs < 5 × 10 17 cm -3 ). We also fabricated an undoped BaSi2 film for comparison.…”

Device operation of P‐ion‐implanted n‐BaSi2/p‐Si heterojunction solar cells

“…These values are acceptable for electron transport layers of BaSi 2 solar cells. The mobility of P‐ion‐implanted BaSi 2 films shows a much lower value than that of MBE‐grown Sb‐ and As‐doped BaSi 2 films 29,34 …”

“…The mobility of P-ion-implanted BaSi 2 films shows a much lower value than that of MBE-grown Sb-and As-doped BaSi 2 films. 29,34 F I G U R E 5 Annealing time dependence for carrier concentration and mobility of P-ion-implanted BaSi 2 films. Open square and triangle indicate p-type conductivity while full symbols show n-type conductivity.…”

Recent Progress Toward Realization of High‐Efficiency BaSi2 Solar Cells: Thin‐Film Deposition Techniques and Passivation of Defects

“…Because the top of the valence band of BaSi 2 is mostly composed of Si p states, [18,19,88,93] replacement of some of the Si atoms in BaSi 2 with group 15 elements like P, As, and Sb forms n-type BaSi 2 . [15,94] However, handling of these elements is very difficult, Reproduced with permission. [57] Copyright 2020, Japan Society of Applied Physics.…”