Low-temperature semiconductor band-gap thermal shifts: shifts from ordinary acoustic and from piezoacoustic coupling
- Stony Brook Univ., NY (United States)
At low temperature, the experimental gap of silicon decreases as . The main reason is electron-phonon renormalization. Furthermore, the physics behind the -power law is more complex than has been realized. Renormalization at low by intraband scattering requires a nonadiabatic treatment in order to correctly include acoustic phonons and avoid divergences from piezoacoustic phonon interactions. The result is an unexpected low term with positive coefficient , and power for nonpiezoelectric materials, and power for piezoelectric materials. The acoustic phonons in piezoelectric semiconductors generate a piezoelectric field, modifying the electron-phonon coupling. However, at higher , thermally excited acoustic phonons of energy and intraband excitation energies become comparable in size. Above this temperature, the low and higher intraband acoustic phonon contributions to rapidly cancel, leaving little thermal effect. Then the contribution from interband scattering by acoustic phonons is dominant. This has the power law for both nonpiezoelectric and piezoelectric semiconductors. The shift can then have either sign, but usually reduces the size of gaps as increases. It arises after cancellation of the terms that appear separately in Debye-Waller and Fan parts of the acoustic phonon interband renormalization. The cancellation occurs because of the acoustic sum rule.
- Research Organization:
- State Univ. of New York (SUNY), Albany, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- FG02-08ER46550
- OSTI ID:
- 1535833
- Alternate ID(s):
- OSTI ID: 1341284
- Journal Information:
- Physical Review B, Vol. 95, Issue 3; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Experimental determination of the bare energy gap of GaAs without the zero-point renormalization
|
journal | December 2019 |
Experimental determination of the bare energy gap of GaAs without the zero-point renormalization | text | January 2019 |
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