Hot Electron Transport in Two-dimensional SiGe/Si Quantum Wells

Abstract

The hot carrier energy loss rate in a two-dimensioal electron gas in SiGe/Si quantum well has been theoretically studied and carrier concentration ranging from 1.0x1012 to 5.0x1014 m-2. The energy loss rate in this highly non-parabolic system is dominated by acoustic deformation potential scattering, whereas the acoustic piezoelectric scattering is negligible. We also studied variation of energy loss rate with thickness of various quantum wells.

Introduction

I. INTRODUCTION

In general the two-dimensional (2D) system is now well understood. Low-dimensional semiconductors (LDS) structures have observed much attention due to their excellent importance and applications in Electronics and Device applications [1-5]. One of such important study is the electron-phonon interaction which explores the use of these LDS structures in high frequency ultrasonic generators and high frequency moderators as device applications. Under high electric field, the electron-phonon interaction in LDS structures play an important role in determining the transport properties viz, electron energy relaxation, mobility, phonon drag and diffusion thermopower, hall effect etc,. Due to the advanced crystal growth techniques and favorable energy gap in GaAs, GaInAs, GaSb, InSb structures, a lot more of experimental and theoretical studies have been carried out in literature over the last three to four decades in the above said transport properties. High power, high frequency and high temperature electronic devices usually requires group III nitride materials and are observed suitable for device applications [6]. Most devices are designed to operate under high electric field. At a high electric field, the electrons equilibrate at a much higher temperature than the lattice temperature. The determination of the temperature of electrons under electric field heating conditions in the steady sate provides useful information about electron-phonon interactions involved in the energy relaxation process. GaN has many applications in optoelectronic and electronic device technologies.

One might have anticipated that SiGe hole or electron systems would behave in a similar fashion to Si-MOSFETs because they are not expected to be piezoelectrically active. However, there are no data on electron systems, and previous thermopower work on a hole system was inconclusive [7, 8] in that the data were at relatively high temperatures (1.5-15 K) where it is difficult to distinguish the various hole-phonon (h-p) scattering mechanisms. The e-p (or h-p) interaction can also be probed by carrier energy loss. The energy loss rate depends on the carrier-phonon energy relaxation time, whereas phonon-drag thermopower reflects the carrier-phonon momentum relaxation time  [9,10]. Thus the two types of measurement provide different but complementary ways to investigate carrier-phonon scattering. Previous measurements on the energy loss rates in SiGe electron systems are in accord with expectations. They agree with calculations assuming only screened deformation potential electron-phonon coupling [11, 12]

At low temperatures, the deformation potential scattering has a stronger temperature dependence, the precise form of which depends on the mechanism of electron-phonon scattering. Systems with screened, piezoelectric e-p scattering of the carriers, e.g., GaAs based structures, have been shown to give a T4 dependence of drag [13] whereas those with only screened deformation-potential (DP) scattering show a T6 dependence [14]. One might have anticipated that SiGe hole or electron systems would behave in a similar fashion to Si-MOSFETs because they are not expected to be piezoelectrically active. The electron-phonon interaction can also be probed by carrier energy loss. The energy loss rate depends on the carrier-phonon energy relaxation time, whereas phonon-drag thermopower reflects the carrier-phonon momentum relaxation time [15]. Thus the two types of measurement provide different but complementary ways to investigate carrier-phonon scattering. Previous measurements on the energy loss rates in SiGe electron systems are in accord with expectations. They agree with calculations assuming only screened deformation potential electron-phonon coupling [11, 12]. However, similar work on SiGe hole systems (where the 2D hole gas resided in a Si1-xGex well) gave loss rates inconsistent with this mechanism. Early measurements were analyzed in terms of a screened, piezoelectric h-p coupling, but more recent work [16]

Leaned towards unscreened deformation potential coupling (these two mechanisms are difficult to distinguish because both give the same power law dependence on T at low temperatures), with a small unscreened piezoelectric term contributing at temperatures < 0.5 K. The present thermopower measurements throw new light on this problem.

Conclusion

The dependence of energy loss rate in SiGe/Si quantum well through acoustic deformation potential and acoustic piezoelectric scattering on the carrier temperature were calculated. The dynamical screening of the electron-phonon interaction was taken into account. Consideration of the dynamical screening effect will reduce the energy loss rate considerably. Acoustic deformation potential scattering is the dominant scattering mechanism at low temperature as compared to acoustic piezoelectric scattering was observed in this SiGe heterostructure same as that of other GaAs, GaN, GaAlAs heterostructures.

References

[1] B S Lisesivdin, S B Lisesivdin, N Balkan, G Atmaca, P Navin, H Cakmak and E Ozbay, Metallurgical and Materials Transactions-A, 46A, 1565 (2015) [2] M D Yang, Y W Liu, J L Shen, C W Chen, G C Chi, T Y Lin, W C Chou, M H Lo, H C Kuo and T C Lu, J. Appl. Phys. 105, 013526 (2009) [3] A Ilgaz, S Gokden, R Tulek, A Teke, S Ozcelik and E Ozbay, Eur. Pjus. J. Appl. Phys. 55, 30102 (2011) [4] Mehmet Ari and Hulya Metin, J. of Optoelectronics and Ad. Materials, 11, 648 (2009) [5] B K Ridley, Rep. Prog. Phys. 54, 169 (1991) [6] H Celik, M Cankutaran, N Balkan and A Bayrakli, Semicond. Sci. Technol. 17, 18 (2002) and references therein. [7] O. A. Mironov, I. G. Gerleman, P. J. Phillps, E. H. C. Parker, M. Tsaousidou and P. N. Butcher, Thin Solid Films 294, 182 (1997) [8] S. Agan, O. A. Mironov, M. Tsaousidou, T. E. Whall, E. H. C. Parker, P. N. Butcher, Microelectronic Engineering, 51-52, 527 (2000) [9] A. Miele, R. Fletcher, E. Zaremba, Y. Feng, C. T. Foxon and J. J. Harris, Phys. Rev. B 58, 13181 (1998) [10] M. Tsaousidou, P. N. Butcher and G. P. Triberis, Phys. Rev. B 65, 165304 (2001) [11] G. Stoger, G. Brunthaler, G. Bauer, K. Ismail, B. S. Meyerson, J. Lutz and F. Kuchar, Phys. Rev. B 49, 10417 (1994) [12] G. Stoger, G. Brunthaler, G. Bauer, K. Ismail, B. S. Meyerson, J. Lutz and F. Kuchar, Semic. Sci. Technol. 9, 765 (1994) [13] R. Fletcher, M. Tsaousidou, P. T. Coleridge, Z. R. Wasilewski and Y. Feng, Physica E 12, 272 (2002) [14] R. Fletcher, V. M. Pudalov, Y. Feng, M. Tsaousidou ad P. N. Butcher, Phys. Rev. B56, 12422 (1997) [15] M. Tsaousidou, P. N. Butcher and G. P. Triberis, Phys. Rev. B 65, 165304 (2001) [16] G. Ansaripour, G. Braithwaite, M. Myronov, O. A. Mironov, E. H. C. Parker and T. E. Whall, Appl. Phys. Lett. 76, 1140 (2000) [17] S S Kubakaddi, Kasala Suresha and B G Mulimani, Semicond. Sci. Technol. 17, 1 (2002) [18] S S Kubakaddi, Kasala Suresha and B G Mulimani, Physica E, 18, 475 (2003) [19] Kasala Suresha, J. Critical Rev. 05, 7 (2018) [20] Kasala Suresha, S S Kubakaddi and B G Mulimani, Physica E, 21, 143 (2004)

Copyright

Copyright © 2023 Kasala Suresha. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.