Non-melting super-resolution near-field apertures in Sb–Te alloys

Abstract

Structure of the optical phase change memory alloy, Ag-V-In-Sb-Te, determined by optical spectroscopy and electron diffractionThe super-resolution near-field structure permits the formation of short-lived subdiffraction limit apertures that channel electromagnetic energy at the aperture boundary. This effect is commonly observed when a laser is focused onto a thin film of Sb based material. The aperture formation within Sb, Sb 2 Te 3 , Sb 2 Te, and SbTe is investigated by time resolved optical pump-probe techniques and found to occur without melting. Ab initio modeling has shown a threshold-like change in the optical properties below the melting temperature which leads to the formation of a near-field aperture. This threshold is shown to be a consequence of thermally induced misalignment of p-type bonding.

Enhanced crystallization of GeTe from an Sb2Te3 template

“…Thus, a decrease in the overall crystallization time of Sb 2 Te 3 templated GeTe is to be expected. To check this, a pump-probe laser static tester 11,15 was used to measure the minimum crystallization time of crys-Sb 2 Te 3 templated GeTe and untemplated GeTe. Figure 2 shows the transmission of the probe laser beam as a function of time and pump power through an amorphous 20 nm thick GeTe film deposited on a 5 nm thick Sb 2 Te 3 template layer.…”

Direct measurement of the near-field super resolved focused spot in InSb

“…Despite the good results, the detailed underlying physical mechanism of the Super-RENS effect, created by heating a sub-wavelength area with the incident focused laser, still has to be fully explained. The most recent contribution in this direction was given by Simpson et al for SbTe materials [11]. In their study, they demonstrated that thermal vibrations can disturb the p-orbital interaction present in the octahedral coordination of the crystalline Sb alloys, resulting in a local and reversible refractive index change.…”

Nonlinear absorption of Sb-based phase change materials due to the weakening of the resonant bond

“…It needs to be pointed out that the mechanism responsible for the weakening of resonant bond is attributed to lattice expansion, which is different from the misalignment of p-orbits reported by Simpson. 8 The thin films with this kind of absorption characteristics exhibit a higher transmittance when irradiated by a stronger laser. This model can thus account for the giant SA observed in the Sb-based PCMs.…”

“…We believe that the crystal lattice expansion is dominant and a gradual change of the optical properties is noticed. However, the higher laser intensity causes higher temperature, the higher temperature causes some torsion in the p-orbital bonds, 8 and this leads to a threshold-like change in the material's refractive index, accordingly.…”

“…However, the response time of the thermal-induced nonlinearity in Sbbased films is found to be in the order of 10 ns. 8 The short response time is possible because the disturbing of resonant bond does not require thermal diffusion and long distance atom movement. The thermal effect induces a giant SA coefficient for Sb 2 Te 3 in the order of 10 À2 m/W, and the values used in the calculation are common for Sb-based PCMs.…”