Electronic and thermoelectric properties of nanograting layers

1495 8 6047 1 16697 document 6047 1757-899X_60_1_012025.pdf application/pdf 83f2adb891def28935175c52cf12d86c MD5 973297 2014-06-18 10:35:20 http://eprints.iliauni.edu.ge/1495/1/1757-899X_60_1_012025.pdf 1495 1 1 application/pdf text en public

1757-899X_60_1_012025.pdf

6050 2 16707 document 6050 lightbox.jpg image/png e457f5c094412884764bfa7f28a27484 MD5 13053 2014-06-18 10:45:37 http://eprints.iliauni.edu.ge/1495/3/lightbox.jpg 1495 3 3 image/png other Thumbnails conversion from text to thumbnail_lightbox ge public

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http://eprints.org/relation/isVersionOf http://eprints.iliauni.edu.ge/id/document/6047 http://eprints.org/relation/isVolatileVersionOf http://eprints.iliauni.edu.ge/id/document/6047 http://eprints.org/relation/issmallThumbnailVersionOf http://eprints.iliauni.edu.ge/id/document/6047 archive 15 disk0/00/00/14/95 2014-06-19 07:58:30 2015-04-02 08:15:48 2014-06-19 07:58:30 conference_item show Tavkhelidze A. avtandil.tavkhelidze@iliauni.edu.ge Electronic and thermoelectric properties of nanograting layers pub QC fac_eng public keynote Recently, new quantum features have been observed and studied in the area of nanostructured layers. Nanograting (NG) on the surface of the thin layer imposes additional boundary conditions on electron wave function and forbids some quantum states. Electrons, rejected from the forbidden quantum states, have to occupy states with higher energy. In the case of semiconductor materials, electrons rejected from the valence band have to occupy empty quantum states in the conduction band. Such increase in conduction band electron concentration n can be termed as geometry-induced doping or G-doping. G-doping is equivalent to donor doping from the point of view of the increase in n. However, there are no ionized impurities. This preserves charge carrier scattering to the intrinsic semiconductor level and increases carrier mobility. G-doping involves electron confinement to NG layer. Here, we investigate the system of multiple NG layers forming a series of homo junctions. Si and GaAs homojunctions were studied and G-doping levels of 1018-1019 cm-3 were obtained. We also study a system composed of NG layer and an additional top layer forming periodic series of p–n junctions. In such system, charge depletion region develops inside the NG and its effective depth reduces, becoming a rather strong function of temperature T. Consequently, T-dependence of chemical potential magnifies and Seebeck coefficient S increases. We investigate S in the system of semiconductor NG layer having abrupt p–n junctions on the top of the grating. Analysis made on the basis of Boltzmann transport equations shows dramatic increase in S. At the same time, other transport coefficients remain unaffected by the junctions. Calculations show one order of magnitude increase in the thermoelectric figure of merit ZT relative to bulk material. 2014 The 13th International Symposium on Advanced Materials (ISAM-2013) conference TRUE http://iopscience.iop.org/1757-899X/60/1/012025/