Origin of the atypical temperature dependence of carrier density in quench-condensed bismuth films

Identify the mechanism that produces the observed lack of a consistent increase in carrier density with temperature in quench-condensed bismuth films, as extracted from Hall measurements between 4.1 K and 296 K, and determine how factors such as Bi(110) versus Bi(111) texture, strain induced by different substrates, and quantum confinement contribute to this behavior.

Background

In room-temperature bismuth films, carrier density decreases upon cooling, consistent with semimetallic behavior involving carrier freeze-out. However, in quench-condensed films the carrier density does not consistently increase with temperature, deviating from expectations.

The authors suggest that an interplay of texture, strain, and quantum confinement could be responsible, but the specific origin remains unresolved and requires further investigation.

References

The reason for the unusual dependence on temperature of carrier density in QC-Bi films is presently unknown, but correlates with the unusual growth conditions.

— Comparative study of room temperature and quench condensed bismuth films: morphology and electronic characteristics  (2604.00369 - Kirina et al., 1 Apr 2026) in Section 3.3, Electronic Characteristics