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胶体半导体量子点的光电性质研究

胶体半导体量子点的光电性质研究. 张家雨，崔一平. 东南大学电子工程系. 北京， 2009 年 5 月. 半导体纳米材料由于量子局域效应呈现许多迥异于体材料的性质，例如其尺寸能大幅度地调节其能带结构，这在荧光、激光发射、太阳能电池和光电调制等方面有广泛的应用前景 。. 国内外已对半导体量子结构进行了几十年的深入研究，目前半导体一维量子结构－－量子阱和超晶格已得到广泛应用，其二 / 三维量子结构－－量子线 / 点已有三十年的广泛研究，提出了各种制备方法。. 目前研究较多的量子点制备方法有半导体外延生长（以 MBE 为代表）和化学胶体方法等.

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胶体半导体量子点的光电性质研究

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  1. 胶体半导体量子点的光电性质研究 张家雨，崔一平 东南大学电子工程系 北京，2009年5月

  2. 半导体纳米材料由于量子局域效应呈现许多迥异于体材料的性质，例如其尺寸能大幅度地调节其能带结构，这在荧光、激光发射、太阳能电池和光电调制等方面有广泛的应用前景。半导体纳米材料由于量子局域效应呈现许多迥异于体材料的性质，例如其尺寸能大幅度地调节其能带结构，这在荧光、激光发射、太阳能电池和光电调制等方面有广泛的应用前景。 国内外已对半导体量子结构进行了几十年的深入研究，目前半导体一维量子结构－－量子阱和超晶格已得到广泛应用，其二/三维量子结构－－量子线/点已有三十年的广泛研究，提出了各种制备方法。 目前研究较多的量子点制备方法有半导体外延生长（以MBE 为代表）和化学胶体方法等

  3. Fabrication of Quantum Dots (QDs) MBE deposition group III-V, IV semiconductor Good stability; Compatible with the semiconductor technology; Easy to fabricate electrically-driven device Electrically-pumped MBE QDs’ Lasing has been realized, but films with high QDs’density and homogeneous QDs’ size are necessary to improve the properties of the MBE QD lasing

  4. Colloidal synthesis: Group II-VI semiconductor Stability is good with core/shell structures size dispersion is good, Shape is easy to be controlled To fabricate electrically-driven device, carriers’ injection and transportion in colloidal QDs should be improved

  5. Colloidal CdSe quantum dots in our lab 6.4 nm 5.6 nm 4.6 nm Abs / PL Intensity (a.u.) 3.9 nm 3.2 nm Digital picture of CdSe nanocrystal s in toluene with different sizes under UV illumination. 2.9 nm 2.6 nm Wavelength (nm) UV-Vis absorption and photoluminescence (PL) spectra of the as-prepared CdSe nanocrystals with different sizes.

  6. Colloidal Core/Shell quantum dots in our lab Absorption (solid line) and PL spectra (dashed line) for bare-core CdSe NCs and CdSe/CdS core/shell NCs with different shell thickness. Inset: PL QY (circle) and PL FWHM (rectangle) of the CdSe/CdS core/shell NCs versus the number of CdS ML.

  7. Applications Colloidal QDs have been synthesized successfully for about ten years, but their optoelectronic application has not been commercially realized yet. In the following, Quantum-confined Stark effect (QCSE), which can be used in Optoelectronic modulators, is as an example. Hhz Hez E Heh

  8. Problem of QCSE in Colloidal QDs phonon bottleneck effect photoionization random electric field near the QDs Science 278, 2114 (1997) QCSE is an electric field effect Clear ensemble QCSE shift has not been observed yet

  9. We have observed a clear QCSE red-shift in electroluminescent spectra ITO/PVK:QDs/Al Voltage-dependent EL (Constant Temperature) The EL peak exhibits a redshift when the applied voltage is increased: Quantum-confined Stark effect

  10. Strong ensemble QCSE absorption have been observed in our lab ITO/PVK:QDs/SiO2/ITO

  11. polarizable character The polarizability is 3.6×106 and 2.9×106 Å3 for the first absorption peak and the emitting peak, respectively

  12. broadening of the absorption peaks weakening of the oscillator strength Advantage: tunneling of carriers out of confined zone Due to 3D confinement, the QDs’ QCSE exbibits better Stark behavior than QWs’ QCSE. Nature 437, 1334 (2005)

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