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 (Sn
₂
$\text{S}_{6}^{4-}$
and Sn
₂
Se
$_{6}^{4-}$
) and thiocyanate (SCN
$^{-}$
). It is found that Sn
₂
$\text{S}_{6}^{4-}$
and Sn
₂
Se
$_{6}^{4-}$
-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.