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Charge Dynamics and Optolectronic Properties in HgTe Colloidal Quantum Wells
Clément Livache1,2, Eva Izquierdo2, Bertille Martinez1
1Institut des NanoSciences de Paris, Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588 , 4 place Jussieu, 75005 Paris, France.
Nano Letters
|June 10, 2017
Summary
We control the electronic properties of mercury telluride (HgTe) 2D colloidal quantum wells using surface chemistry. This tuning impacts carrier type and photoconductivity, paving the way for novel electronic devices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Mercury telluride (HgTe) 2D colloidal quantum wells are promising materials for electronic applications.
- Controlling their electronic and transport properties is crucial for device optimization.
Purpose of the Study:
- To investigate the influence of capping ligands on the electronic and transport properties of HgTe 2D colloidal quantum wells.
- To understand the relationship between surface chemistry, carrier type, and photoconductivity.
Main Methods:
- Synthesis of HgTe 2D colloidal quantum wells with varying capping ligands.
- Measurement of electronic and transport properties (e.g., conductivity, photoconductivity).
- High-resolution X-ray photoemission spectroscopy (HRXPS) for electronic structure determination.
- Time-resolved photoemission spectroscopy (TR-PES) for probing transport relaxation dynamics.
Main Results:
- Demonstrated control over p-type and n-type majority carrier concentration by selecting specific capping ligands.
- Observed significant impact of surface chemistry on photoconductivity.
- Attributed carrier type modulation to the hybridization of an n-doped HgS layer formed by sulfur capping.
- Tuned photocurrent rise and fall times (100 μs to 1 ms) via gate bias.
- Identified geometrical factors, not fundamental trapping processes, as the primary limitation for current performance based on TR-PES measurements revealing faster relaxation (100-500 ns).
Conclusions:
- Surface chemistry, specifically capping ligands, offers a powerful tool to tune the electronic and transport properties of HgTe 2D colloidal quantum wells.
- The observed effects are linked to surface hybridization and formation of distinct electronic layers.
- Photoconductivity dynamics are influenced by gate bias and temperature, with performance limitations stemming from device geometry rather than intrinsic material relaxation rates.
