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 (Sn2S64- and Sn2Se64-) and thiocyanate (SCN-). It is found that Sn2S64- and Sn2Se64--capped QD/IGZO phototransistors show enhanced optoelectronic characteristics such as responsivity (R) of 3.06 x 10(3) A W-1 and 8.8 x 10(2) A W-1, respectively, and photodetectivity (D*) of 2.1 x 10(13) Jones and 6.18 x 10(11) Jones, respectively, compared with SCN--capped CdSe QD/IGZO phototransistors ( R of 1.21 x 10(3) A W-1 and D* of 2.02 x 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.