Effects of Hydrogen Passivation on Near-Infrared Photodetection of n-Type β-FeSi₂/p-Type Si Heterojunction Photodiodes

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

“…The obtained device specific detectivity at 300 K in zero bias conditions is 1.2 × 10 9  cm × Hz 1/2 /W at a wavelength of 1300 nm. The calculated value exceeds the results for β -FeSi 2 films on average152324 and is inferior in only in comparison with a passivated Si/ β -FeSi 2 heterostructure25.…”

“…At room temperature, the photoresponse and external quantum efficiency values at the wavelength of 1300 nm in the avalanche mode ( R  = 20 mA/W; η  = 2%) are quite comparable with those of β -FeSi 2 thick films on Si ( R  = 3–15 mA/W; η  = 1–2%)23242526 and even exceed the values obtained for a β -FeSi 2 homojunction32. At the same time, we took advantage of the conventional Si p-n junction and expanded the functionality of the silicon diode structure in NIR photodetection, increasing the photoresponse by more than two orders of magnitude at important wavelengths for optical communications by adding a small amount of Fe to the initial system, while for the same results it is necessary to use films of β -FeSi 2 (90–100 nm of Fe)23242526.…”

“…At room temperature, the current under illumination is only slightly greater than the dark current, which can be associated with the relatively small amount of the β -FeSi 2 (seven layers with only 0.4 nm of Fe in each) in comparison with the β -FeSi 2 films on Si substrates, which show one order of magnitude difference between dark current and current under illumination1523242526. On the other hand, embedded β -FeSi 2 NCs form mainly scattered layers (Fig.…”

“…At the same time, we took advantage of the conventional Si p-n junction and expanded the functionality of the silicon diode structure in NIR photodetection, increasing the photoresponse by more than two orders of magnitude at important wavelengths for optical communications by adding a small amount of Fe to the initial system, while for the same results it is necessary to use films of β -FeSi 2 (90–100 nm of Fe)23242526. Moreover, it was shown that embedding of β -FeSi 2 NCs resulted in an increase of the sensitivity at the silicon absorption edge by more than one order of magnitude.…”

Mechanism of Carrier Transport at Low Temperatures in n-Type Beta-FeSi2/p-Type Si Heterojunctions Fabricated by Facing-Target Direct-Current Sputtering

“…At present, semiconducting iron disilicide (β-FeSi2) is a promising candidate for integration with silicon for optoelectronic applications because of its remarkable electrical and optical properties [1][2].It possesses a high optical absorption coeffcient greater than 105 cm-1 at 1.2 eV and a direct optical band gap of 0.85 eV above an indirect optical band gap of 0.74eV.The values of band gap correspond to optical fiber telecommunication wave lengths ranging from1.31 to 1.55μm [3].Moreover, β-FeSi2 thin films can be grown epitaxial yon Si substrates with small lattice mismatches (2-5%) [3].It is also an ecologically friendly material because of the non toxicity of its component elements (Si and Fe) [4].…”