Two dimensional phonon-drag thermopower in Si0.87Ge0.13/Si (001) heterostructure grown by MBE

Results of thermoelectric power measurements are presented for two dimensio nal hole gas (2DHG) formed at the normal interface of modulation boron dope d Si/Si0.87Ge0.13 /(001) Si fully strained heterostructure for the first ti me in the temperature range 1.5 to 25 K. The modulation-doped 2DHG sample h as carrier sheet density p(s) of 2 x 10(11) cm(-2) and its mobility value m u is 1.11 x 10(4) cm(2) V-1 s(-1) at liquid He-4 temperature. The thermoele ctric power is found to be dominated by the phonon drag contribution. A fit to phonon-drag thermopower theory yields a value of 5.5 eV for the screene d acoustic phonon deformation potential. A Kohn anomaly is observed at simi lar to 3.5+/-0.5 K. (C) 2000 Elsevier Science B.V. All rights reserved.