Four-point-probe measurement of conductivity vs temperature of an 80-nm film heated at a rate of 1.6 K/min (see Ref. 6). The dashed line is for heating up to 270 °C at 1.2 K/min and cooling to room temperature. The transition temperature at 1.6 K/min is estimated to be 430 K from the maximum of the slope of conductivity vs temperature.
The assumed exponential conductivity profile in the phase-change layer (continous-line) and its slope (dashed line). Also shown is how the transition length parameter is related to the extent of the amorphous to crystalline transition region.
Geometry of the tip/electrode and material structure used to develop the electrothermal model of the recording system. Symmetry is assumed about the center of the coordinate system which is located at the middle of the tip.
Transition length as a function of the dimensionless ratio for different phase-change layer thicknesses. The parameters for the calculations are , , , , , , , , , and . The indicated numbers refer to the following phase-change materials: (1) , (2) AglnSbTe, and (3) .
Calculated transition lengths for different thermal boundary conditions between the underlayer and substrate, simulating different substrate materials. For underlayer/dielectric , for underlayer/thermal conductor , and for underlayer/thermal insulator . Also shown are the calculated thermal characteristic lengths for each boundary. The calculation parameters are the same as in Fig. 4 and using .
Measured transition temperatures as functions of the heating rate for obtained from four-point-probe resistivity measurements in Ref. 6, compared with the calculated values from Eq. (A3). The parameters used for the calculations were obtained from isothermal optical reflectivity measurements in Ref. 35 and are , , and . It was also assumed that .
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