Temperature Dependence of the Optical Absorption Edge ofp-Type SnTe

Abstract

The optical-absorption coefficient and index of refraction of SnTe were measured at 300, 77, and 12°K over the photon energy range between 0.14 and 0.64 eV. The specimen was a single-crystal SnTe film with a hole concentration of 3.6X10 19 cm -3 . The threshold of absorption by bound carriers at 12°K occurs at a photon energy less than 0.38 eV. This suggests that the smallest direct gap is considerably less than the gap of 0.30 eV which Esaki and Stiles have deduced from tunneling measurements. In contrast to the temperature dependence of the tunneling gap, the temperature dependence of the absorption edge suggests that the temperature coefficients of the direct gaps that lie in the photon energy range investigated are positive. However, these coefficients decrease rapidly with decreasing photon energy, suggesting that direct gaps between states sufficiently close to the band edge will have negative temperature coefficients. The electricsusceptibility effective mass was also determined. Its variation from 0.066w 0 at 300°K to 0.057wo at 12°K is consistent with the observation of direct gaps having positive temperature coefficients. We propose new features for the band structure of SnTe which account for these results, as well as previously reported results for the PbTe-SnTe alloy system.

Investigating the effect of temperature dependent many-body interactions on bulk electronic structures and the robust nature of (001) surface states of SnTe

“…Moreover, it is clearly found from the figure that the calculated values of direct bandgap at the L-point from PBEsol and G 0 W 0 are ∼0.30 and ∼0.31 eV, respectively. In case of direct bandgap, these calculated values are in good agreement with the experimentally observed optical absorption edge 48,49 , where optical gap is defined as the smallest direct gap between VB and CB at room temperature. At this point, one should keep in mind that Bylander et al 48 proposed the possibility of smaller indirect bandgap for SnTe, which is also evident from this calculation.…”

Magnetic order effects on electric susceptibility hole mass of Sn1-x MnxTe

“…Burke and Riedl [25] have proposed an explanation of this inconsistency, supported by recent calculations [18,26] It is then due to the fact that this semiconductor has a small gap, the interband interaction being responsible for this complexity of the energy surfaces.…”

Electrical and optical properties of SnEuTe and SnSrTe films

“…11 Absorption coefficient of direct gap IV-VI compound semiconductor is given by 12 However, the detail of band edge structure has not been studied owing to the high carrier concentration.…”