Effective Mass from Seebeck Coefficient

Effective Mass from Seebeck Coefficient

Engineering semiconductor devices requires an understanding of the effective mass of electrons and holes. Effective masses have historically been determined in metals at cryogenic temperatures estimated using measurements of the electronic specific heat. Instead, by combining measurements of the See...

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Bibliographic Details
Published in:Advanced functional materials Vol. 32; no. 20
Main Authors: Snyder, Gerald Jeffrey, Pereyra, Alessandro, Gurunathan, Ramya
Format: Journal Article
Language:English
Published: Hoboken Wiley Subscription Services, Inc 01-05-2022
Wiley Blackwell (John Wiley & Sons)
Subjects:
Carrier density
Cryogenic temperature
Current carriers
effective mass
Electromagnetism
Electronic structure
electronic transport
Free electrons
Grain boundaries
Hall effect
Materials science
Room temperature
Seebeck coefficient
Seebeck effect
Semiconductor devices
semiconductor materials
Temperature
Thermoelectric materials
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Summary:Engineering semiconductor devices requires an understanding of the effective mass of electrons and holes. Effective masses have historically been determined in metals at cryogenic temperatures estimated using measurements of the electronic specific heat. Instead, by combining measurements of the Seebeck and Hall effects, a density of states effective mass can be determined in doped semiconductors at room temperature and above. Here, a simple method to calculate the electron effective mass using the Seebeck coefficient and an estimate of the free electron or hole concentration, such as that determined from the Hall effect, is introduced mS∗me=0.924(300KT)(nH1020cm−3)2/3[3(exp[|S|kB/e−2]−0.17)2/31+exp[−5(|S|kB/e−kB/e|S|)]+|S|kB/e1+exp[5(|S|kB/e−kB/e|S|)]] here mS∗ is the Seebeck effective mass, nH is the charge carrier concentration measured by the Hall effect (nH = 1/eRH, RH is Hall resistance) in 1020 cm−3, T is the absolute temperature in K, S is the Seebeck coefficient, and kB/e = 86.3 μV K−1. This estimate of the effective mass can aid the understanding and engineering of the electronic structure as it is largely independent of scattering and the effects of microstructure (grain boundary resistance). It is particularly helpful in characterizing thermoelectric materials. The effective mass is a fundamental property of electronic structure and transport but has been difficult to measure experimentally. An experimental effective mass parameter, termed the Seebeck effective mass, is derived here from measurements of the Seebeck coefficient and charge carrier concentration. Analysis of the Seebeck effective mass is used to identify changes in electronic bandstructure directly from transport measurements.
Bibliography:USDOE
DE‐AC02‐76SF00515
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.202112772