High-detectivity and -stability multilayer-graphene/Si-quantum-dot photodetectors with TiOx back-surface passivation layer. (November 2019)

• Record Type: Journal Article
• Authors: Shin, Dong Hee; Jung, Dong Hwan; Choi, Suk-Ho
• Is Part Of: Dyes and pigments. Volume 170(2019)
• Publication Date: 2019-11
• Subjects: Graphene -- Multilayer -- Si quantum dot -- Photodetector -- TiOx -- Detectivity -- Stability; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2019.107587
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: We first report Si quantum dots (SQDs)-embedded SiO2 (SQDs:SiO2 ) multilayers (MLs)/Si photodetectors (PDs) using multilayer graphene (MLG) transparent conductive electrode (TCE) and TiOx back-surface passivation layer. With increasing number of graphene layer ( L n ) to 5, the sheet resistance of the MLG TCE sharply decreases to ∼273 Ω/sq whilst the work function gradually increases to ∼4.71 eV, indicating p-type doping, useful for collection of photo-excited carriers at the MLG/SQDs:SiO2 MLs interface. At L n = 4, the PD without TiOx exhibits best performance of 0.340 AW -1 responsivity (R) and 3.21 × 10 9 cm Hz 1/2 W −1 specific detectivity (D*) at the peak wavelength. With TiOx on the back side of Si wafer ( L n = 4), the R slightly increases to 0.351 AW -1, but the D* is greatly enhanced to 9.42 × 10 11 cm Hz 1/2 W −1, resulting from the sharp reduction of the dark current by the suppression of the carrier recombination at the Si/TiOx interface. The PD performance is almost consistent for 1000 h in air, irrespective of the use of the TiOx layer. These behaviors are much better than ever achieved in graphene/Si wafer PDs. Highlights: First use of multilayer graphene as an electrode for Si-quantum-dot photodetectors. High detectivity of 9.42 × 10 11 cm Hz 1/2 W −1 is obtained with the use of TiOx layer. The responsivity is almost consistent for 1000 h in air, indicating high stability.