Article

Temperature dependence of semiconductor band gaps

University of Strathclyde, Glasgow, G4 ONG Scotland, United Kingdom
Applied Physics Letters (Impact Factor: 3.52). 07/1991; DOI: 10.1063/1.104723
Source: IEEE Xplore

ABSTRACT The application of a simple three‐parameter fit to the temperature dependence of semiconductor band gaps is justified on both practical and theoretical grounds. In all trials the fit is numerically better than that obtained using the widely quoted Varshni equation. The formula is shown to be compatible with reasonable assumptions about the influence of phonons on the band‐gap energy. Approximate analytical expressions are derived for the entropy and enthalpy of formation of electron‐hole pairs in semiconductors.

1 Bookmark
 · 
45 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The elemental composition, structural, optical and electronic properties of p-type Cu3BiS3 thin films are investigated. The films are shown to be single phase orthorhombic, with a measured composition of Cu3.00Bi0.92S3.02. A surface oxidation layer is also clarified using energy dependent X-ray microanalysis. Photoreflectance spectra demonstrate two band gaps (EgX =1.24 eV and EgY =1.53 eV at 4 K) associated with the X and Y valence sub-bands. The photocurrent excitation measurements suggest a direct allowed nature of EgX. Photoluminescence spectra at 5 K reveal two broad emission bands at 0.84 and 0.99 eV quenching with an activation energy of 40 meV.
    Energy Procedia 12/2014; 60.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Carbon dots are cost-effective, environmental friendly, and biocompatible nanoparticles with many potential applications in optoelectronics and biophotonics. Their dual fluorescence bands were observed and could be attributed to core and surface state emission. We also conduct temperature-dependent fluorescence measurements from cryogenic to room temperatures. The dual emission bands exhibit similar temperature dependence. The strong electron–electron interactions and weak electron–phonon interactions could account for the very broad photoluminescence (PL) band even at 77 K. Our experimental results also suggest that carbon dots exhibit similar temperature behavior as metallic quantum dots (nanoclusters) but are different from inorganic semiconductor quantum dots. Here, for the first time, we present the temperature-dependent spectroscopic results to shed some light on the presently unclear fluorescence mechanism.
    The Journal of Physical Chemistry C 11/2012; 116(48):25552–25557. · 4.84 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this work, we investigated the temperature-dependent luminescence of bovine serum albumin-protected Au25 nanoclusters and the correlation with their structure. Our experiments reveal that the red luminescence consists of two bands, namely, band I at 710 nm and band II at 640 nm. The temperature dependence of band I exhibits similarity to semiconductors, such as a red shift of emission and bandwidth broadening upon increasing temperatures due to electron–phonon and electron–defect/surface scattering. In contrast, band II exhibits different temperature dependence. It is concluded that band I exclusively originates from the icosahedral core of 13 Au(0) atoms and band II dominantly arises from the [−S–Au(I)–S–Au(I)–S−] staples. Moreover, with increasing temperatures, the intensity of band I and band II decreases. A similar activation energy was extracted, which is attributed to thermally activated defect/surface trapping. In addition, the relaxation from band II to band I was found to be inactive from 300 K down to 77 K.
    The Journal of Physical Chemistry C. 05/2012; 116(21):11830–11836.

Full-text (2 Sources)

Download
217 Downloads
Available from
Jun 14, 2014