On The Thermoelectric Power in Degenerate Narrow Gap Semiconductors in the Presence of a Strong Magnetic Field
- PDF / 761,928 Bytes
- 4 Pages / 417.6 x 639 pts Page_size
- 8 Downloads / 212 Views
ON THE THERMOELECTRIC POWER IN DEGENERATE NARROW GAP SEMICONDUCTORS IN THE PRESENCE OF A STRONG MAGNETIC FIELD Kamakhya Prasad Ghatak *
Badal De**
Departuent of bhlectronics Zngineering, Faculty of Engineering qnd Technology, University of Jadavpur, Calcutta-700032, India John Brown 'b & C Inc., 333 Ludlow Street, P.C.Box 1422, Conneeticut-06907, USA. ABSTRACT In this paper we have studied the thermoelectric power under strong magnetic field in degenerate semiconductors on the basis of fourth order in effective mass theory and taking into account the interactions of the conduction electrons, heavy-holes, light-holes and split-off holes respectively. The results obtained are then compared to those derived on the basis of the well-known three-band Kane model. It is found, takir-w r-Hgl_xCdxTe as an example, that the magneto-thermo power increases with decreasing electron concentration and increasing magnetic field respectively for both the models in an oscillatory way. The oscillations are due to SdH effects and the theoretical snelysis in accordance with fourth order in effective mass theory is in agreement with the experimental observation as reported elsewhere. In addition, the corresponding results for parabolic energy bands have also been obtained as special cases of our generalized foriulations. In recent years there has been considerable interest in studying the various types of narrow gap semiconductors becau-
se of their i-portance in device technology /l/. The ternary semiconductors is a very important narrow -ap coopounds which find extensive applications in infrared detectors and its band gap can be varied to cover the entire spectral range from 0.8 to 3O/um. It is also used inphotovoltaic detector arrays in 8-12Fam wave bands /2/. Though considerable work has already been done, nevertheless it appears from the literature that the ther,;uelectric power under strong magnetic quantization (TPM in such narrow gap semiconductors has yet to be investigated on the basis of fourth order in effective mass theory and taking into account the interactions of the conduction electrons and heavy, light and split-off holes respectively. We shall also use the well-known magneto three-band Tane model
for the purpose of comparison. 'Ie shall p2ot the doping end magnetic field dependences of the TPYM by usin- both types of band models and taking n-JLgl-xCdxTe as an example.
The energy spectrum in the presence of a i.uantizing magnetic field H can be expressed on the basis of fourth order effective mass theory and taking into account the interactions of the (nconduction, splip-off holes /3/ as S=-J+ ÷ )wo+heay (h -Xz / light 2T) +- and (m!'/mo) (ýWol o+-'•o"i(wo)
*(n+ 4)+
K1 (kw 1E) C(2k 2/2ni;)-(K1/
~g)/(n4+
4'wo~ jt2k2 /2m)21
where the notations are defined in /3/. The use of (l) to the expression of the electron concentration as Mat. Res. Soc. Symp. Proc. Vol. 234. @1991 Materials Research Society
leads
60
'max
no =(4H/ Tti-)
, r)+T(n
/-((n
2_0
'F,9rL7
(2)
n=O where the notations are defined in /3/. k
Data Loading...
