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) of3.06× 103A W−1and8.8× 102A W−1, respectively, and photodetectivity (D^) of2.1× 1013Jones and6.18× 1011Jones, respectively, compared with SCN⁻-capped CdSe QD/IGZO phototransistors (Rof1.21× 103A W−1andD^of2.02× 1011Jones). Independently, all these devices exhibit 1/flow-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.