QUANTUM CONFINEMENT EFFECT IN HgTe NANOCRYSTALS AND VISIBLE LUMINESCENCE

Abstract

Mercury Telluride (HgTe) nanocrystals with a mean size of 5.35 nm have been synthesized by an electrochemical technique. Structural analysis by transmission electron microscopy and glancing angle X-ray diffraction studies indicate the presence of cubic phase HgTe nanocrystals in the deposit. Optical absorption measurements reveal two well resolved excitonic peaks around 578.5 nm and 550 nm attributed to heavy hole valence band (HVB)-conduction band (CB) and light hole valence band (LVB)-CB transitions, respectively, and suggest a band opening of bulk inverted narrow band gap HgTe as a result of strong quantum confinement effect (QCE). Visible photoluminescence (PL) of HgTe nanocrystals indicates free exciton transition around 579.5 nm as observed from the PL measurement at 300 K along with a bound exciton dominated band around 588 nm. Micro-Raman measurements at 300 K indicate the 1LO vibrational mode at 142.6 cm −1 shifted by 6 cm −1 from its standard bulk value and confirm the QCE.

Biocatalytic growth of semiconductor nanowires

“…2͑a͒, 2͑c͒, and 2͑b͒, respectively. Comparing the above optical absorption analysis with our previous work, 23 it is clear that the nano-crystallites are particulate in nature giving well resolved excitonic peaks corresponding to heavy hole valence band to conduction band transition and light hole valence band to conduction band transition respectively. Similarly, Fig.…”

Size quantization effect in highly stable UV emitting HgTe nanoparticles: Structure and optical properties

“…Being a robust stable material, HgTe has attracted huge interest from scientists and technologists 11,[13][14][15][16][17][18][19][20] for wide applications in electronic and optoelectronic devices. 11 and 12͒ at room temperature, effective mass m ‫ء‬ = 0.0129m 0 ͑m 0 is the rest mass of electron͒, and Bohr exciton radius, a B = 40.1 nm generally used as an infrared ͑IR͒ absorbing materials for IR applications.…”

“…11 and 12͒ at room temperature, effective mass m ‫ء‬ = 0.0129m 0 ͑m 0 is the rest mass of electron͒, and Bohr exciton radius, a B = 40.1 nm generally used as an infrared ͑IR͒ absorbing materials for IR applications. In our earlier works, [17][18][19] we have demonstrated the visible luminescence from HgTe NP films prepared by electrodeposition where control of stoicheometry is a problem. [21][22][23][24][25][26][27] Since a B is relatively large compared to other II-VI group of semiconductors, the synthesis route be such that one can easily achieve a size less then 40.0 nm so as to observe a strong SQE in HgTe NPs.…”

Electric-field-induced self-assembled one-dimensional nanostructures in CdX and HgX (X=Se, Te) thin films

“…Rath et al [37] reported on large blue shift in the band gap for HgTe (2.4 eV) for a particle size of $ 5 nm. From TEM images (Figs.…”