Silicon‐silicide quasi‐zero dimensional heterostructures for silicon based photonics, opto‐ and thermoelectronics

Abstract

Optimization of growth parameters has permitted to create monolithic nanocomposites with buried nanocrystallites (NCs) of iron and chromium disilicides, polycrystalline nanocomposites with buried Mg2Si NCs and epitaxial MnSi1.74 nanoislands on Si(111) substrate. Grown quasi‐zero dimensional heterostructures with multilayers of β‐FeSi2 NCs atop silicon p‐n junction have demonstrated the range expansion of photoelectrical sensitivity up to 1.8 µm and strong room temperature electroluminescence at 1.2 – 1.6 µm. A new approach to the selective doping of embeddded nanocrystallites inside silicon matrix has been developed on the base of the successive formation of ordered superstructures of metals (Ag, Sb) together with silicide island formation. Nanocomposite layers with n‐ and p‐type conductivity and huge Seebeck coefficient (550‐750 µV/K) in the Si‐p/β‐FeSi2 NCs/Si‐p and Si/Mg2Si NCs/Si‐p and Si/Mg2Si NCs/Si‐n nanocomposites have been created and tested. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Enhancement of the Si p-n diode NIR photoresponse by embedding β-FeSi2 nanocrystallites

“…On the other hand, embedded β -FeSi 2 NCs form mainly scattered layers (Fig. 1) in silicon matrix, with a surface density of 10 11  cm −2 at most, as was shown in our previous works2027. Thus, the part of the NIR light passes through the structure without photocarrier generation.…”

“…Thus, the relation between relative built-in voltages is about 1 to 4000, suggesting that the applied bias drops at the Si p-n junction and does not cause a change in the energy level differences and barrier height at the β -FeSi 2 /Si heterojunction in equilibrium state. The values of the work function of Si and β -FeSi 2 needed to construct the band diagram were taken from the literature data3437, and the Fermi level positions depending on temperature and doping level were calculated following Sze27 using the value of the density of states in the valence band of p- type β -FeSi 2 obtained by Kasaya et al 38.…”

Transport properties of β-FeSi2

“…1,2) Possible application of high refractive semiconducting silicides to high index contrast photonic crystals has been proposed. 8,9) Reports on electroluminescence at 1.5-1.6 µm, 10,11) strong photoluminescence at 1.54 µm, 12) as well as publications on advanced β-FeSi 2 based materials as rodlike, 13) nanodots, 14,15) nanowires, 16,17) and nanocomposites 18,19) increase possibilities of the β-iron disilicide utilizations.…”