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Optical Properties of Semiconductor Quantum Dots:
Low Temperature Nano-scale Imaging and Spectroscopy system is designed to explore the novel opto-electronic properties of semiconductor nanostructres with high spatial, spectral and temporal resolutions.
The system is based on a conventional microscope with long working distance objectives. However, the novel techniques developed by our group provide capabilities of isolating the spectral features of individual light emitting units such as quantum dots with nano-meter scale precision. This simple optical imaging system has high signal collection efficiency as well as the flexibility to be combined with sophisticated ultra-fast spectroscopy techniques.
- Home built Microscope with Mitutoyo 50x and 100xNIR objectives
- Cryostats
- Oxford Instruments' Microstat: Hi Res and Microstat
- Temperature Range: 4-350K
- Low thermal drift and high temperature stability
- ARS Cryo closed-cycle He cryostat
- Continuous operation for days
One of the major barriers in studying the optical properties of semiconductor QDs is to isolate the spectral features of a single QD out of a large inhomogeneous ensemble. This barrier has been overcome by either using near field probes or micron scale apertures to reduce the number of QD under observation. Although near-field techniques provide very high spatial resolution, their poor collection efficiency and technological complexity severely limit overall effectiveness and flexibility to combine with other existing optical spectroscopic techniques. In far-field optics based techniques, micron scale apertures have been successfully utilized to the study the spectroscopic properties an individual QD in low density SAQD's and naturally formed QD system. However, for a high density QD ensemble, an aperture of 1 micron in diameter can only reduced the number of probed QD's to ~ a hundred. The spectra collected through the aperture usually composed of a group of atomically sharp spectral lines. It is essential to further isolate the spectral feature of a single QD out of that jungle of peaks.
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