Temperature dependence of the energy bandgap of multi-layer hexagonal boron nitride
The temperature dependence of the energy bandgap of hexagonal boron nitride (h-BN) has been probed via photoluminescence emission characteristics of a donor-to-acceptor pair transition in a 20-layer h-BN epilayer. The results indicate that the universal behavior of bandgap decreasing with temperatur...
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Veröffentlicht in: | Applied physics letters 2017-09, Vol.111 (13) |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The temperature dependence of the energy bandgap of hexagonal boron nitride (h-BN) has been probed via photoluminescence emission
characteristics of a donor-to-acceptor pair transition in a 20-layer h-BN epilayer. The results indicate that the universal behavior of bandgap
decreasing with temperature is absent in multi-layer h-BN.
Below 100 K, the bandgap energy variation with temperature, Eg vs. T, is
dominated by the electron-phonon coupling and conforms to the common behavior of redshift
with an increase in temperature. At T > 100 K, the bandgap shows an unusual blueshift
with temperature, which can be attributed to the unique behavior of the in-plane thermal
expansion coefficient of h-BN that becomes negative above
around 60 K. Although both graphite and h-BN have negative
thermal expansion coefficients in a broad temperature range, graphite has a zero energy
bandgap, which makes h-BN a unique semiconductor to exhibit
this unusual temperature dependence of the energy bandgap. |
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ISSN: | 0003-6951 1077-3118 |
DOI: | 10.1063/1.4994070 |