Research

Molecular beam epitaxy (MBE) is used by our group to grow nanostructured IV-VI semiconductor heteroepitaxial materials. A picture of our Mod Gen II MBE growth chamber is shown at the right. Source materials include PbSe, PbTe, SnSe, Se, Sr (or Eu), BaF2, and dopants. Growth substrates include BaF2, PbSe and Si. A bandgap versus lattice parameter plot for the binary and pseudobinary alloys that can be grown with this system is show below. These materials have direct interband transitions in the mid-infrared region of the electromagnetic spectrum (3 microns to 20 microns). Applications for these materials include lasers and detectors for laser absorption spectroscopy instruments. Recent accomplishments in this research area include demonstration of above room temperature continuous wave mid-infrared photoluminescence from IV-VI semiconductor multiple quantum well (MQW) structures grown on BaF2 [1,2] and silicon [3,4] substrates (see figure at lower right) and observation of L-valley degeneracy removal in (111)-oriented MQWs [5,6] .

SEMICONDUCTOR MATERIALS
Molecular beam epitaxy (MBE) is used by our group to grow nanostructured IV-VI semiconductor heteroepitaxial materials. A picture of our Mod Gen II MBE growth chamber is shown at the right. Source materials include PbSe, PbTe, SnSe, Se, Sr (or Eu), BaF2, and dopants. Growth substrates include BaF2, PbSe and Si. A bandgap versus lattice parameter plot for the binary and pseudobinary alloys that can be grown with this system is show below. These materials have direct interband transitions in the mid-infrared region of the electromagnetic spectrum (3 microns to 20 microns). Applications for these materials include lasers and detectors for laser absorption spectroscopy instruments. Recent accomplishments in this research area include demonstration of above room temperature continuous wave mid-infrared photoluminescence from IV-VI semiconductor multiple quantum well (MQW) structures grown on BaF2 [1,2] and silicon [3,4] substrates (see figure at lower right) and observation of L-valley degeneracy removal in (111)-oriented MQWs [5,6] .
	Click on the plots for better quality pdf file
References [1] P. J. McCann, K. Namjou, and X. M. Fang, "Above-Room-Temperature Continuous Wave Mid-Infrared Photoluminescence from PbSe/PbSrSe Quantum Wells", Applied Physics Letters 75, 3608 (1999). (pdf 57KB) [2] X. M. Fang, K. Namjou, I. Chao, P. J. McCann, N. Dai, and G. Tor, "Molecular Beam Epitaxy of PbSrSe and PbSe/PbSrSe Multiple Quantum Well Structures for use in Mid-Infrared Light Emitting Devices", Journal of Vacuum Science and Technology 18, 1720 (2000).(pdf 64KB). [3] D. W. McAlister, P. J. McCann, K. Namjou, H. Z. Wu and X. M. Fang, "Mid-IR Photoluminescence from IV-VI Layers Grown on Silicon", Journal of Applied Physics 89, 3514 (2001). (pdf 46.6KB). [4] H. Z. Wu, P. J. McCann, O. Alkhouli, X. M. Fang, D. McAlister, K. Namjou, N. Dai, S. J. Chung, and P. H. O. Rappl "Molecular beam epitaxial growth of IV-VI multiple quantum well structures on Si(111) and BaF2(111) and optical studies of epilayer heating", Journal of Vacuum Science and Technology B 19, 1447 (2001). (pdf 210KB). [5] H. Z. Wu, N. Dai, M. B. Johnson, P. J. McCann, Z. S. Shi, "Unambiguous Observation of Subband Transitions from Longitudinal Valley and Oblique Valleys in IV-VI multiple Quantum Wells", Applied Physics Letters 78, 2199 (2001). ( pdf 53.7KB). [6] H. Z. Wu, N. Dai, and P. J. McCann, "Experimental determination of deformation potentials and band nonparabolicity parameters for PbSe", Physical Review B 66, 045303 (2002). (pdf 98KB)