Shao Jun

Bismuth Effects on Electronic Levels in GaSb(Bi)/AlGaSb Quantum Wells Probed by Infrared Photoreflectance

GaSb(Bi)/Al0.2Ga0.8Sb single quantum wells are characterized by a Fourier transform infrared spectrometerbased photoreflectance method at 77 K. Spatially direct and indirect transitions between the electronic levels at and above the effective band gap are well resolved. The shifts of the electronic levels with Bi incorporation are identified quantitatively. The results show that the upshift of the valence band edge is clarified to be dominant, while the Bi-induced downshift of the conduction band edge does exist and contributes to the band gap reduction in the GaSbBi quantum-well layer by (29±6)%.

Spectral Resolution Effects on the Lineshape of Photoreflectance

Spectral resolution effects on the lineshape of photoreflectance (PR) spectroscopy is experimentally investigated. PR measurements are performed on HgCdTe epilayer and InAs/GaAs quantum dot (QD) low-dimensional samples at low temperatures in a spectral resolution range from 8 to 0.5 meV. The results indicate that the resolution affects not only the identification of narrow PR features, but also the determination of critical-point energies of identified PR features, and a spectral resolution of as high as 0.5 meV may be necessary for low-dimensional semiconductors. The spectral resolution is indeed a crucial parameter, for which the step-scan Fourier transform infrared spectrometer-based PR technique is preferable.

Temperature-dependent Photoluminescence of Silicon Nanocrystals Embedded in SiO 2 Matrix

——————————— *Corresponding authors. Email: xinchen@mail.sitp.ac.cn; ndai@mail.sitp.ac.cn Received December 20, 2017; accepted February 9, 2018. Supported by the National Key R&D Program of China(No.2016YFA0202200) and the Fund of the Youth Innovation Promotion Association of Chinese Academy of Sciences(CAS) and the Humboldt(AvH).

RECENT PROGRESS AND POTENTIAL IMPACT OF MODULATION SPECTROSCOPY FOR NARROW-GAP HgCdTe

Recent progress of infrared photoreflectance and modulated photoluminescence techniques was outlined with special attention focused on the significant improvement of signal-to-noise ratio,spectral resolution and time consumption relative to the conventional techniques.Application of these techniques to molecular beam epitaxially grown HgCdTe films was given as examples,from which the potential impact of the techniques was foreseen on the optical study of narrow-gap semiconductors and inter-subband transition of wide-gap semiconductors with low-dimensional structures.