Thermo emf in a two-dimensional electron-hole system in HgTe quantum wells in the presence of magnetic field. The role of the diffusive and the phonon-drag contributions
E. B. Olshanetsky1, Z. D. Kvon1,2, G. M. Gusev3, M. V. Entin1, L.I. Magarill1, and N. N. Mikhailov1
1Institute of Semiconductor Physics, Novosibirsk 630090, Russia
2Novosibirsk State University, Novosibirsk 630090, Russia
3Instituto de Fsica da Universidade de São Paulo, São Paulo 135960-170, SP, Brazil
Received September 09, 2020, published online November 24, 2020
We present an experimental study of the thermo emf of a two-dimensional electron-hole system in a 21 nm HgTe quantum well in the presence of magnetic field. The first experimental observation of Nernst–Ettingshausen effect in a 2D semimetal is reported. The comparison between theory and experiment shows that the thermo emf is determined by two contributions: the diffusion and the phonon drag, with the latter contribution several times greater than the first. The conclusion is drawn about the important role of electron-hole scattering in the formation of both thermoelectric power mechanisms.
Key words: quantum well, 2D semimetal, diffusion, phonon drag.