Electroreflectance in SbSI

Abstract

The electroreflectance (ER) of SbSI has been measured in a wide temperature range between 1.6 and 3.3 eV with linearly polarized light. The technique of transverse ER was used and the first and second harmonics of ER were measured simultaneously. The effects of domain reorientation, complementary light illumination, the specimen damping and electric field vector rotation on the sample surface are investigated. It is shown: (a) that the induced reflectivity change is not caused by purely Kern-Harbekeeffect, but depends on the piezoelectric strain; (b) that separated from the deformation component, the ER spectrum is close to the hmodulation spectrum and may be interpreted in a similar way.

Absorption Edge Anomalies in Polar Semiconductors and Dielectrics at Phase Transitions

“…Rearrange (15) in the form of a sum of terms, containing K as a parameter and not, where As follows from (19) and (ZO), with an anomaly a ( T ) (6 + 0), the AE jump value depends on the choice of the K value, while Y does not depend on this choice and is a constant for the particular substance and PT. Depending on the relation of amplitudes and signs of Y and 6 there may be several versions of A E f behaviour as a function of In (K,/K) [26]. When the signs of Y and 6 are different, there may exist a K* value, a t which the AE jump equals zero even in the presence of E,, KO, and a ( T ) jumps.…”

Disordering effect on optical absorption processes in CuInP2S6 layered ferrielectrics

“…In the unpolar paraelectric phase ∆E g α (T) = 0. To describe the energy gap temperature behavior of CuInP 2 S 6 crystals in the PT range we apply a known expansion of the variation ∆E g α (T) in a series of even degrees of the order parameter η [24]. Being restricted by the first term of the expansion, it is given by…”

Temperature variation of optical absorption edge in Sn2P2S6and SnP2S6crystals

“…These displacements correspond to the order parameter of the ferroelectric PT.anions, the second one-third -by Sn4 ' ions and the last one-third remains unoccupied. The average length of Sn-S bonds is 2.582(9) A, but since tin atoms are displaced with respect to one of the sulphur layers, one group of Sn-S bonds is shorter (2.5732 A) than the other (2.590 A).…”