Photoresponse Properties of Semiconducting BaSi₂Epitaxial Films Grown on Si(111) Substrates by Molecular Beam Epitaxy

Abstract

n-Type BaSi 2 epitaxial films with 900 nm thickness were grown on Si(111) by molecular beam epitaxy, and striped Au electrodes were formed on the surface. Photocurrents were clearly observed for photons with energies greater than 1.25 eV under bias voltages applied between the electrodes, and this increased sharply with increasing photon energy to attain a maximum at approximately 1.70 eV. The external quantum efficiency increased with the bias voltage and reached approximately 7% at 1.70 eV for a bias voltage of 7 V. This value is 100 times larger than the highest value ever reported for semiconducting silicide films. #

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].…”

Formation of BaSi2 heterojunction solar cells using transparent MoOx hole transport layers

“…The EQE began to increase sharply for photon energies larger than 1.3 eV, which is in good agreement with the band gap of BaSi 2 and our previous results. 34,35 The valley-like structure at around 2.5 eV (ca. 500 nm) in the spectrum was caused by light interference in the ITO layer.…”

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.…”