FOCUS

My current research effort focuses on nanostructures based on III-V and II-VI compound semiconductors grown by epitaxial techniques. The materials studied have direct energy bandgaps and thus are suitable for photonic applications (emitters, detectors, modulators). Of particular interest are the wide-gap II-VI semiconductors, such as ZnSe, which for the last five years have been used for the fabrication of lasers in the blue-green. A variety of nondestructive optical techniques in the visible and near infrared are used: reflectivity, absorption, photoluminescence, and Raman spectroscopies. Electronic states, impurities, and vibrational modes are investigated using these methods.

SELECTED PROJECTS

• The properties of a two-dimensional electron gas in n-type modulation doped ZnSe/ZnCdSe and ZnSe/ZnCdMnSe quantum well structures
• The observation of type I and type II excitons in ZnTe/CdSe quantum wells
• Internal transitions among excitons and donors in semiconductor heterostructures using optically detected resonance

PUBLICATIONS

• G. Kioseoglou, J. Haetty, H. C. Chang, H. Luo, A. Petrou, T. Schmiedel, and P. Hawrylak. Magnetoluminescence study of n-type modulation doped ZnSe/ZnCdSe quantum well structures. Phys. Rev. B 55:4628 (1997).
• W. Y. Yu, S. Stoltz, A. Petrou, J. Warnock, and B. T. Jonker. Metastable excitons in ZnSe/ZnFeSe quantum wells. Phys. Rev. B 56:6862 (1997).
• J. Haetty, M. H. Na, H. C. Chang, H. Luo, and A. Petrou. Fabrication of flexible monocrystalline ZnSe-based foils and membranes. Appl. Phys. Lett. 69:1609 (1996).
• M. S. Salib, H. A. Nickel, G. S. Herold, A. Petrou, B. D. McCombe, R. Chen, K. K. Bajaj, and W. Schaff. Observation of internal transitions of confined excitons in GaAs/AlGaAs quantum wells. Phys. Rev. Lett. 77:1135 (1996).
• S. T. Lee, J. Haetty, A. Petrou, P. Hawrylak, M. Dutta, J. Pamulapati, P. G. Newman, and M. Taysing-Lara. Interband transitions in AlGaAs/AlAs quantum well structures. Phys. Rev. B 53:12912 (1996).

Fig. 1 Oscillations in the intensity of band-edge luminescence with magnetic field from an n-type modulation doped ZnSe/ZnCdSe single quantum well (electron areal density n=1.8x10¹² cm^-2). The two intensity maxima at 14 and 24 tesla correspond to transitions from the ,=2 and ,=1 conduction band Landau levels to the top of the valence band.