Wang, Lin-Jun, Gang Cao, Tao Tu, Hai-Ou Li, Cheng Zhou, Xiao-Jie Hao, Zhan Su, Guang-Can Guo, Hong-Wen Jiang, and Guo-Ping Guo. "A graphene quantum dot with a single electron transistor as an integrated charge sensor." Applied Physics Letters 97, no. 26 (2010): 262113.

Hi Chimezie Eguzo

The number of electrons involved in each case comes from the way the Coulomb blockade (CB) i.e. the repulsion Coulomb barrier UCB between the quantum dot (QD) and the environment, is dealt with.

- In a single-electron transistor (SET) which is basically a quantum dot (QD) Field Effect Transistor (FET), the Coulomb blockade effect is controlled through bias voltages applied to the FET Source-Drain polarization bias and Gate-Drain modulation bias. In this way electrons are allowed to tunnel through the QD device from the source to the drain in a finely controlled manner down to ‘’one by one’’ hence SET denomination of this ‘’mesoscopic’’ quantum device.

Here is a good review on the topic of SQET’s :

file:///C:/Users/A/Downloads/Single_Electron_Transistor_SET_Operation_and_Appli.pdf

- In the case of a QD sensor, there are no control electrodes as is the case in SET. In QD sensor, the QD is immerged in the medium usually a biological analyte in view of biodetection through photoluminescence or fluorescence processes (optoelectronic processes). Here, the number of electrons involved depends also on the coulomb blockade barrier which depends in a complex manner essentially on the size of the QD and the nature of the analyte (biological medium to analyze). Here, the number of the electrons is in general higher than in previous SET case.

Here is a good review on the topic of SQET’s :

https://d1wqtxts1xzle7.cloudfront.net/49329736/Quantum-Dot-Based_Photoelectrochemical_S20161003-29582-jlg0c8.pdf?1475541542=&response-content-disposition=inline%3B+filename%3DQuantum_Dot_Based_Photoelectrochemical_S.pdf&Expires=1597265910&Signature=X8aEf12RHVf1GySXFcv30~lihbvUc~bIcjmevsEA3peUF0QLZetOWWJAlmrRky85r09XRnDoo2FCVF5HWk7ff3nW0eb142Q9cXyT3-Fhr72J~ihqKaVvfVP9I7CyO~dwu5rVJquH8EQ3AzfAiZ6lmhqmlleR4BllVCgxYBSVJ6PXDOoeRt~gCaST4fAmOi28-zSkKalfysA2N2l84~o7RLvU7jICynfkskpJARkR55e71YOYwdUOKW2C2XHQQEo9gfNxrwchZPNEp9FM2~Cj6uVbrIeHduFJoVzEClp-AXHT~etM7zhTR0tCsJlL1dzUm2~HU6Oo1Z3cp~doHBkWlQ__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZAf

Best of Luck,

Prof A. Kadri

You can find the differences in the following link https://www.nature.com/articles/s41598-018-31268-x