Title :
Electrical properties of /spl beta/-FeSi2 bulk crystal grown by horizontal gradient freeze method
Author :
Shibata, H. ; Makita, Y. ; Kakemoto, H. ; Tsai, Y. ; Sakuragi, S. ; Katsumata, H. ; Obara, A. ; Kobayashi, N. ; Uekusa, S. ; Tsukamoto, T. ; Tsunoda, T. ; Imai, Y.
Author_Institution :
Electrotech. Lab., Tsukuba, Japan
Abstract :
The growth of bulk iron silicide by Horizontal Gradient Freeze (HGF) method was achieved using different growth and annealing conditions. Two types of annealing process, in-situ annealing and ex-situ annealing, were examined. Three types of samples were prepared and examined; (i) samples which were not applied any annealing processes, (ii) samples which were applied in-situ annealing, and (iii) samples which were applied both in-situ and ex-situ annealing. The influence of annealing and growth conditions upon the material qualities was examined and discussed, putting special emphasis on the structural properties and electrical properties. Results of the X-ray diffraction revealed that only the in-situ annealing was not sufficient for the peritectic reaction from /spl alpha/+/spl epsi/ eutectic to peritectic /spl beta/-phase. However, it was revealed that, if the ex-situ annealing is applied after the in-situ annealing, the condition of 900/spl deg/C for 200 hours is enough for the ex-situ annealing to obtain almost single /spl beta/-phase. It was also confirmed in the aspect of electrical properties that ex-situ annealing at 900/spl deg/C for 300 hours is enough to realize electrically semiconducting /spl beta/-FeSi/sub 2/. The sample prepared under such a condition exhibited p-type conductivity with hole concentration and hole mobility about 5.68/spl times/10/sup 17/ cm/sup -3/ and 1.36 cm/sup 2/Ns, respectively.
Keywords :
annealing; crystal growth from melt; crystal structure; electrical resistivity; iron compounds; semiconductor materials; thermoelectric power; /spl beta/-FeSi/sub 2/ bulk crystal; 200 h; 300 h; 900 C; FeSi/sub 2/; X-ray diffraction; annealing conditions; electrical properties; hole concentration; hole mobility; horizontal gradient freeze method; p-type conductivity; peritectic reaction; structural properties; Annealing; Cooling; Crystalline materials; Crystals; Furnaces; Iron; Powders; Solids; Temperature; Thermoelectricity;
Conference_Titel :
Thermoelectrics, 1996., Fifteenth International Conference on
Conference_Location :
Pasadena, CA, USA
Print_ISBN :
0-7803-3221-0
DOI :
10.1109/ICT.1996.553257