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Analy sis of microinhomogeneity of irradiated Si by Hall and magnetoresistance effects

Analy sis of microinhomogeneity of irradiated Si by Hall and magnetoresistance effects. J.Vaitkus, A.Mekys, J.Storasta. Vilnius University, Institute of Materials Science and Applied Research. Basic principle. V. - +. A. Scattering by clusters:. Transient photo-Hall.

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Analy sis of microinhomogeneity of irradiated Si by Hall and magnetoresistance effects

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  1. Analysis of microinhomogeneity of irradiated Si by Hall and magnetoresistance effects J.Vaitkus, A.Mekys, J.Storasta Vilnius University, Institute of Materials Science and Applied Research 10 th RD 50 Workshop, Vilnius, 2007.06.04

  2. Basic principle V - + A Scattering by clusters: 10 th RD 50 Workshop, Vilnius, 2007.06.04

  3. Transient photo-Hall 10 th RD 50 Workshop, Vilnius, 2007.06.04

  4. Calculation scheme As = 10-12cm-2 for ionized scattering center. 10 th RD 50 Workshop, Vilnius, 2007.06.04

  5. Hall factor Hall scattering factor rH is defined by following expressions: The relaxation time for individual scattering process often follows a power law: Variation of Hall scattering factor with total impurity density Nimp. In n-type Si. Experimantal points: -x- 77K, -o- 300K. Solid curves: calculated (from Kirnas et al., 1974) 10 th RD 50 Workshop, Vilnius, 2007.06.04

  6. Inhomogeneities l1 l1 grain VA R. H. Bube model: l2 VH [R. H. Bube, Appl. Phys. Lett. 13, 136 (1968)] 10 th RD 50 Workshop, Vilnius, 2007.06.04

  7. Inhomogeneities V. G. Karpov, A. J. Shik and B. I. Schklovskij (1982): The cells of typical clusters: I, II and III. Dashed lines indicates the equipotential lines 10 th RD 50 Workshop, Vilnius, 2007.06.04

  8. Inhomogeneities J. D. Albrecht et al. (1999): When the mobility is limited solely by dislocation scattering and this process can be modeled by scattering form a line charge, rH can be estimated by computing the average momentum relaxation time. It follows from the analytic expression: K2 is the second order modified Bessel function and is the Debye screening length Specifically, rH is smaller than but close to 1.93 In summary, it is clear that to assume rH =1 in analyzing low-field Hall data often leads to errors of 30% (and occasionally as much as 100%) in carrier density and mobility 10 th RD 50 Workshop, Vilnius, 2007.06.04

  9. 10 th RD 50 Workshop, Vilnius, 2007.06.04

  10. This is not bipolarity, clusters barriers block the Hall voltage. Magnetoresistivity does not see the ionized scattering centers –regions where the the current flows are scatters different way. 10 th RD 50 Workshop, Vilnius, 2007.06.04

  11. ~0,36 eV activation found at the highest irradiation doze. The activation developed from lower value – that is not doping level, that is barrier. Mr. Mott was here… At higher dozes, amorphous zones appeared. 10 th RD 50 Workshop, Vilnius, 2007.06.04

  12. Screening EC EV EB1 EB2 Cluster’s potential overlaps when n’ decreases to 1011 cm-3 at irradiation doses above 1014 cm-2 10 th RD 50 Workshop, Vilnius, 2007.06.04

  13. The photo-carriers are trapped between barriers that they screen! EFFECTIVE darkness concentration seems low. 10 th RD 50 Workshop, Vilnius, 2007.06.04

  14. Photoconductivity relaxation 10 th RD 50 Workshop, Vilnius, 2007.06.04

  15. FTIR 10 th RD 50 Workshop, Vilnius, 2007.06.04

  16. Annealing 80C 10 th RD 50 Workshop, Vilnius, 2007.06.04

  17. 10 th RD 50 Workshop, Vilnius, 2007.06.04

  18. 10 th RD 50 Workshop, Vilnius, 2007.06.04

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  20. Time resolved photo-Hall {$A+,B-,D-,E+,F-,G+,I-,L-,N+ {$M 32768,0,65536} usesdefaul,invisi,LPTproc,Hco keithhol; ConstKEITHLEY=1;W301_2= varTKl,temp1,temp2,temp3:sin N / /S N2 33.14159 mA 20.0000 V kV + - T S / /N N2 + + - - 10 th RD 50 Workshop, Vilnius, 2007.06.04

  21. 10 th RD 50 Workshop, Vilnius, 2007.06.04

  22. Acknowledgments: I am grateful to Gunnar Lindstroem for complicated and interesting samples  THANK YOU FOR YOUR ATTENTION 10 th RD 50 Workshop, Vilnius, 2007.06.04

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