Photoresponse Properties of Polycrystalline BaSi₂Films Grown on SiO₂Substrates Using (111)-Oriented Si Layers by an Aluminum-Induced Crystallization Method

Abstract

Polycrystalline BaSi2 layers with 300 nm thickness were grown by molecular beam epitaxy on (111)-oriented 100-nm-thick polycrystalline Si layers fabricated by an aluminum-induced crystallization method on SiO2. Photocurrents were clearly observed for photons with energies greater than 1.25 eV when bias voltage was applied between the 1.5-mm-spacing striped Al electrodes formed on the surface. The photoresponsivity increased sharply with increasing photon energy, attaining a maximum at approximately 1.60 eV. The external quantum efficiency increased with the bias voltage and reached approximately 8% at 5 V. This value is larger than that obtained for BaSi2 epitaxial films on Si(111).

Photoresponse properties of BaSi2 epitaxial films grown on the tunnel junction for high-efficiency thin-film solar cells

“…It is important to note that the symmetric J-V characteristics were observed over the 6 wide temperature range, and that the series resistance remained negligibly small at temperatures higher that 200 K. Thus, we may say that the electrical properties of the n + -BaSi 2 /p + -Si junction are satisfactory. later, and also larger than those we have previously reported [12,13]. These results show that a tunnel junction using BaSi 2 was in fact realized.…”

“…Recent reports on the photoresponse properties of BaSi 2 epitaxial layers on Si(111) and polycrystalline BaSi 2 layers on <111>-Si layers formed on SiO 2 by the Al-induced crystallization method have shown that BaSi 2 is a very promising Si-based new material for thin-film solar cell applications [12,13].…”

Potential variation around grain boundaries in BaSi2 films grown on multicrystalline silicon evaluated using Kelvin probe force microscopy

“…It is of significant interest to determine the potential variations in BaSi 2 formed on multicrystalline Si (mc-Si) substrates, especially those around the GBs of the mc-Si substrate. This would provide information on the potential application of a BaSi 2 single-junction solar cell on an inexpensive SiO 2 substrate covered with (111)-oriented polycrystalline Si or Ge layers by Al-induced crystallization (AIC), [34][35][36][37][38] and multijunction or heterojunction solar cells composed of wider band gap (Ba,Sr)(Si,C) 2 silicides [39][40][41][42][43] and mc-Si. This article reports the growth of BaSi 2 layers on a mc-Si substrate by molecular beam epitaxy (MBE), and discusses the crystal orientation determined by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) analyses, and the surface potential distribution around BaSi 2 GBs determined from KFM.…”

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

“…[11][12][13][14] Recently, we have achieved large photoresponsivities for photon energies greater than the bandgap from BaSi 2 epitaxial layers on Si(111) and polycrystalline BaSi 2 layers on h111i-oriented Si films deposited on SiO 2 using an Al-induced crystallization method. 15,16 However, due to large conduction and valence band discontinuities at the BaSi 2 /Si heterointerface, 17 a tunnel junction (TJ) is necessary to assist current flow in a BaSi 2 pn junction diode formed on a Si substrate. In our previous work, we formed a Sb-doped n þ -BaSi 2 /p þ -Si TJ and achieved clear photoresponsivities in undoped n-BaSi 2 overlayers formed on the TJ.…”