Significant photoresponsivity enhancement of polycrystalline BaSi₂ films formed on heated Si(111) substrates by sputtering

Abstract

We fabricated approximately 200-nm-thick BaSi2 films on Si(111) substrates at 600 °C. The formation of BaSi2 was demonstrated by X-ray diffraction and Raman spectroscopy. A reduction in the electron concentration (n = 2 × 1016 cm−3) by 3 orders of magnitude compared to that previously reported (n = 7 × 1019 cm−3) and resultant photoresponsivity enhancement by more than two orders of magnitude were achieved. The photoresponsivity increased with the bias voltage Vbias applied between the top and bottom electrodes, and reached approximately 0.19 A/W at 2.0 eV, room temperature, and |Vbias| = 0.5 V.

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.…”

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

“…Figure 2a shows the Ba and Si atomic ratios of the films. [70] The ratios depend on P, probably because of the significant differences among the atomic weights of Si (28.08), Ar (39.95), and Ba (137.33). The broken lines represent the results of samples sputtered without Ba sources, whereas the solid lines show the results with one plate-like Ba source (1.0 Â 1.5 cm 2 ) on the BaSi 2 target.…”

“…The slight increase in the electron concentration shown in Figure 3c is probably caused by the defects induced in the deposited films due to sputtering under high P BaSi2 . [70] Copyright 2018, Japan Society of Applied Physics. c) Ba and Si atomic ratios as a function of P BaSi2 with two additional Ba sources on the BaSi 2 target.…”

“…b) Deposition rate as a function of P without Ba sources. a,b) Reproduced under the terms of the CC-BY 4.0 license [70]. Copyright 2018, Japan Society of Applied Physics.…”

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

“…Here, we discuss why the Ba-to-Si atomic ratio depends on P. Figure 3(b) shows the experimentally obtained P dependence of deposition rate of sputtered films when the substrate temperature was set at RT to prevent the diffusion of Si atoms from the Si substrate. 25) The increase of P has both positive and negative contributions to the deposition rate due to the increase of both the sputtering yield and the scattering degree between Ar and sputtered particles. The fact that the deposition rate decreased as the P increased suggests that the latter effect appeared significant.…”