Wavelength-selective photodetectors with high quantum efficiency using an optical blocking layer and a field-induced junction on a silicon nanowire

초록

Crystalline silicon nanowires (c-SiNWs) cSiNWs) have unique optical characteristics that enable tuning of their spectral response. However, real-world applications of cSiNWs as multispectral photodetectors are still hampered by their low selectivity and low quantum efficiency (<30%). The primary obstacles include the broad-spectrum light absorption of the bottom crystalline silicon (c cSi) substrate underneath the cSiNWs and the difficulties in forming appropriate p-n junctions on cSiNWs. In this study, an optical blocking layer was applied to block light absorption in the bottom cSi substrate, and atomic-layer deposition-based Al2O3 2 O 3 was employed to form a dopant-free p-n junction on diameter-controlled cSiNWs. Consequently, the maximum external quantum efficiency (EQE) of the fabricated photodetector is 77.4% with remarkable wavelength selectivity. This work removes major stumbling blocks for the use of cSiNWs as selective light spectral band-pass photodetectors.

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