Impact of deposition pressure and two-step growth technique on the photoresponsivity enhancement of polycrystalline BaSi₂ films formed by sputtering

Abstract

We investigate the influence of deposition pressure in the range 0.25−1.0 Pa on the photoresponsivity of 200-nm-thick BaSi2 films grown by sputtering at 600 °C. BaSi2 films formed at 0.8 Pa exhibit a high photoresponsivity. The deposited Ba-to-Si atomic ratio depends significantly on the sputtering pressure. That's why the pressure influences the photoresponsivity. BaSi2 films grown by a two-step growth technique show much higher photoresponsivity almost equivalent to those grown by molecular beam epitaxy. The photoresponsivity reaches 0.75 A/W at 2.0 eV at a bias voltage of 0.5 V applied between the top and bottom electrode.

Fabrication of high-photoresponsivity BaSi2films formed on conductive layers by radio-frequency sputtering

“…This is because we need to set TS at 600 °C upon the formation of BaSi2 films by sputtering. [25][26][27] We see the change in color and aggregates on the surface of sample ITO- O atoms from the ITO underlayers. We ascribed this Raman line to substances such as Ba oxides 35) and Si gel.…”

Zn1–xGexOy Passivating Interlayers for BaSi2 Thin-Film Solar Cells

“…Simulations indicated that the parasitic absorption loss significantly reduced when AZO was used as an ETL, and the photocurrent density absorbed in the 500 nm thick p-BaSi 2 layer increased from 18.0 to 28.0 mA cm –2 . Furthermore, because only one type of conductivity, p-type BaSi 2 , is required, it is easier to apply other methods, such as sputtering, − vacuum deposition, , and close-spaced evaporation . Additionally, we fabricated an n + -AZO/p-BaSi 2 heterojunction solar cell and demonstrated its operation …”

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

“…[15,21] In this review, we focus on the recent progress of BaSi 2 to bridge the gap between the present status and that described in previous review articles. [14,15] Great progress has especially been made in thinfilm deposition techniques [22][23][24][25][26][27][28][29][30][31] and understanding the surface structure of BaSi 2 epitaxial films, [32] the reactions at the air/BaSi 2 and BaSi 2 /Si interfaces during post annealing, [33][34][35][36][37] and understanding the importance of satisfying the stoichiometry. [38,39] By positron annihilation spectroscopy, [39] it has been revealed that the electron concentration increases to %10 18 cm À3 with increasing vacancy-type defects [38] when the Ba/Si atomic ratio is far from the stoichiometric ratio.…”

“…In addition, novel device structures have been proposed, [40][41][42][43][44][45][46][47][48][49][50] and passivation of defects in BaSi 2 has been demonstrated by atomic-hydrogen (H) [51][52][53][54][55][56] and carbon (C) doping. [27,30,57] For deposition techniques, vacuum evaporation of BaSi 2 granules [21][22][23][24][25] and sputtering of BaSi 2 targets [26][27][28][29][30] or cosputtering of Si and Ba targets [31] are suitable to form BaSi 2 films for large-scale deployment on inexpensive substrates like SiO 2 . Large minority-carrier lifetimes (>4 μs) have been obtained for polycrystalline BaSi 2 films by these methods, [27,58] and they are comparable with those of BaSi 2 epitaxial films obtained by molecular beam epitaxy (MBE), [52] showing the superiority of these deposition techniques.…”