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We have epitaxially grown undoped β-FeSi2 films on Si(111) substrates via atomic-hydrogen-assisted molecular-beam epitaxy. β-FeSi2 films grown without atomic hydrogen exhibited p-type conduction with a hole density of over 1019 cm-3 at room temperature (RT). In contrast, those prepared with atomic hydrogen showed n-type conduction and had a residual electron density that was more than two orders of magnitude lower than the hole density of films grown without atomic hydrogen (of the order of 1016 cm-3 at RT). The minority-carrier diffusion length was estimated to be approximately 16 μm using an electron-beam-induced current technique; this value is twice as large as that for β-FeSi2 prepared without atomic hydrogen. This result could be well explained in terms of the minority-carrier lifetimes measured by a microwave photoconductance decay technique. The 1/e decay time using a 904 nm laser pulse was approximately 17 μs, which is much longer than that for β-FeSi2 prepared without atomic hydrogen (3 μs). The photoresponsivity reached 13 mA/W at 1.31 μm, which is the highest value ever reported for β-FeSi2 films. [ABSTRACT FROM AUTHOR]

Abstract: We have fabricated a β-FeSi2 film by metalorganic chemical vapor deposition on a Si(001) substrate with β-FeSi2 seed crystals grown by molecular beam epitaxy, and investigated the crystallinity, surface morphology and temperature dependence of photoresponse properties of the β-FeSi2 film. The surface of the grown β-FeSi2 film was atomically flat, and step-and-terrace structure was clearly observed. Multi-domain structure of β-FeSi2 whose average size was approximately 200nm however was revealed. The photoresponse was obtained in an infrared light region (~0.95eV) at temperatures below 200K. The external quantum efficiency reached a maximum, being as large as 25% at 100K when a bias voltage was 2.0V. [Copyright &y& Elsevier]

Abstract: We have fabricated 200-nm-diameter ferromagnetic resonant tunneling diodes (FM-RTDs) using CaF2/Fe3Si heterostructures on Si(111) substrates, by selected-area molecular beam epitaxy (MBE) using electron-beam (EB) lithography. Clear negative differential resistances (NDRs) were observed in the current–voltage (I–V) characteristics at room temperature (RT). The reproducibility of the I–V characteristics was greatly improved, and approximately 40% of the FM-RTDs showed clear NDRs at RT. [Copyright &y& Elsevier]

Electroluminescence at an emission power of over 0.4 mW is achieved at an emission wavelength of 1.6 μm using a p-Si/β-FeSi2/n-Si double-heterostructure light-emitting diode. This emission power is obtained at room temperature under current injection of 460 mA, corresponding to an external quantum efficiency of approximately 0.1%. Photoluminescence and time-resolved photoluminescence measurements for devices with different thicknesses of β-FeSi2 indicate that radiative recombination rate increased as the thickness of the β-FeSi2 active layer is increased. [ABSTRACT FROM AUTHOR]

We have epitaxially grown p+-Si/β-FeSi2(8 nm)/n+-Si (SFS) light-emitting diodes (LEDs) on Si(001) substrates by molecular-beam epitaxy (MBE) using Ga-doped p+-Si layers (p∼1019 cm-3). 1.6 µm electroluminescence (EL) was realized at room temperature (RT) for the first time for the SFS LEDs prepared without high-temperature annealing. [ABSTRACT FROM AUTHOR]

We have epitaxially grown p-Si/β-FeSi2/n-Si double heterostructures light-emitting diodes (LEDs) on Si(111) substrates by molecular-beam epitaxy. The 1.6 µm electroluminescence intensity measured at room temperature (RT) was improved significantly for LEDs constructed using a thick β-FeSi2 active layer (190 nm) embedded in heavily-doped Si p–n diodes formed on floating-zone Si(111) substrates. The external quantum efficiency was increased up to approximately 0.02% at RT. [ABSTRACT FROM AUTHOR]

Abstract: We have successfully grown a-axis-oriented p-type BaSi2 films on Si(111) by in situ boron (B) doping using molecular beam epitaxy (MBE). The hole concentration in B-doped BaSi2 was controlled in the range between 1017 and 1019 cm−3 at room temperature by changing the temperature of the B Knudsen cell crucible. The acceptor level was estimated to be approximately 23meV. [Copyright &y& Elsevier]