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Séminaire d’Emmanuel Lhuillier

Transport properties of colloidal quantum dots films and its application to photodetection


Emmanuel Lhuillier

LPEM, ESPCI

Transport properties of colloidal quantum dots films and its application to photodetection

My talk will start with some general considerations about colloidal
semiconductor quantum dots. I will in particular highlight how this
system, which is obtained from a chemichal synthesis, has reached a high
level of maturity and can compete with epitaxially grown
heterostructure. Then I will focus on the transport properties of QD and
I will show that two parameters drive the level of conduction which are
the interparticle mobility and carrier density. In my talk I will in
particular interest to HgTe quantum dots and CdSe colloidal quantum
wells.
In a second part I will discuss how it is possible to tune the
interparticle coupling to reach high mobility films. And I will apply
this result to the photoconduction properties of mid infrared (3-5痠)
HgTe QD. I will in particular show how we can improve by two decades the
detectivity of QD based mi-IR photodetector by encapsulating the QD in
the right passivating matrix.
Finally I will expose recent results about the charging of colloidal QD
using solid electrolyte. Our method is applied to colloidal quantum well
and has lead to exceptional performances for electrolyte gated field
effect transistor with record on/off ratio. Carrier densities as high as
1020cm-3 are achieved thanks to bulk doping of the film. We use this
strategy to build phototransistor and bicolor device.