Project 141028B: Spectroscopy of elementary excitations in semimagnetic semiconductors


     In this project we shall investigate the optical and transport properties of narrow band gap semiconductor alloys based on the lead and mercury halchogenides, undoped and doped with the elements of the III group or transitional elements with unfilled d-orbital. In undoped alloys would be investigated phonon properties and electronic structure (electron-phonon and plasmon-phonon interaction). In doped systems would be investigated the effects connected with the existence of mixed valence of the impurity (DX centers): coupling of the electron continuum with the eigenvibrations of the impurity, long-live relaxation processes, persistent photoconductivity and changes in the phonon structure. 

     Within the framework of the proposed project the investigations would be performed through the following topics: 

  1. Investigation of phonon properties of narrow band gap semiconductors Pb1-xMnxTe, Pb1-xGexTe, PbTe1-xSx, Hg1-xMnxTe, Hg1-xMnxSe and Hg1-xCdxTe.

  2. Influence of doping with elements of the III group (Al, Ga, In) and transitional elements with unfilled d-orbital (Cr, Mn, Co, Ni) on optical and transport properties of the lead and mercury halchogenides.

  3. Investigation of phonon properties of quaternary alloys Hg1-xMnxTe1-ySe and Cd1-xMnxTe1-ySey.

  4. Optical and transport properties of narrow band gap semiconductors Hg1-xCdxTe and PbTe: Ga annealed by intensive laser pulses or on some other way.

     Investigations within the first topic represent the groundwork for the other ones. For better incorporation of impurities in crystal structure the synthesis methods of basic crystal are modified. Regarding phonon and electronic structure new materials are obtained whose characteristics should be established. 

     Within the second topic would be investigated effects connected with the doping influence. Firstly, we will investigate the electron activity of impurity (DX centers), the way of its forming and the effects connected with them (persistent photoconductivity, Fermi level pinning and long-live relaxation processes).

     Within the third topic is planned a development of a new model for describing a phonon properties of quaternary alloys. Experimental work will be aimed to the last generation of semi magnetic narrow band gap semiconductors Hg1-xMnxTe1-ySe and Cd1-xMnxTe1-ySey.The particular attention will be devoted to the luminescence effects connected with extremely complex electronic structure.

     The fourth topic includes the investigation of the effects of annealing of the surface of narrow band gap semiconductors by laser radiation or on some other way on their optical and transport properties and to analyze the possibilities to adjust these materials to the specific needs for practical application.

     Raman and infrared spectroscopic methods and Hall experiment will be used to investigate the optical and transport properties of these materials. All measurements would be performed in a temperature range from 300-10K with a magnetic field strength up to B=0.5T with or without controlled additional illumination. Using these spectroscopic methods will be analyzed the influence of the energy, polarization and the power of the incident light. 


Center for Solid State and New Materials :: Projects
Project 1481: Optical and transport properties of lead and mercury halchogenides 
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