Analysis of Low-Frequency Noise in Quantum Dot/Metal-Oxide Phototransistors with Metal Chalcogenide Interfaces

Low-frequency noise measurements are carried out to investigate optoelectronic characteristics of CdSe quantum dot (QD)/indium-gallium-zinc-oxide (IGZO) heterostructured hybrid phototransistor with respect to various QD surface ligands, such as chalcometallate ligands (Sn2 $\text{S}_{6}^{4-}$ and Sn2Se $_{6}^{4-}$ ) and thiocyanate (SCN $^{-}$ ). It is found that Sn2 $\text{S}_{6}^{4-}$ and Sn2Se $_{6}^{4-}$ -capped QD/IGZO phototransistors show enhanced optoelectronic characteristics such as responsivity ( ${R}$ ) of $3.06\times 10$ 3 A W-1 and $8.8\times 10$ 2 A W-1, respectively, and photodetectivity ( ${D}^\ast$ ) of $2.1\times 10$ 13 Jones and $6.18\times 10$ 11 Jones, respectively, compared with SCN $^{-}$ -capped CdSe QD/IGZO phototransistors ( ${R}$ of $1.21\times 10$ 3 A W-1 and ${D}^\ast $ of $2.02\times 10$ 11 Jones). Independently, all these devices exhibit 1/ ${f}$ low-frequency noise dependence in the subthreshold, ohmic, and saturation regimes. In particular, in the ohmic and saturation regime, the low-frequency noise properties follow the bulk mobility fluctuation mechanism for the chalcometallate ligands-based devices, while carrier number fluctuation model is dominant for the SCN $^{-}$ -based devices. Thus, low-frequency noise analysis may provide meaningful information to evaluate important parameters for nanomaterial-based optoelectronics.