Characteristics of N-doped Sb2Te3 Films by X-ray Diffraction and Resistance Measurement for Phase-change Memory

In this paper, characterizations of sputtered undoped and nitrogen-doped Sb2Te3 (ST and STN) films by X-ray diffraction (XRD) and resistance measurements are described and their application of lateral phase-change memory (PCM) is presented. Nitrogen concentration of the films was controlled by changing the flow rate ratio of N2/Ar during sputtering. Resitivity of STN films drops by 3-4 orders of magnitude due to crystallization. Resistivity increase of the STN film (N2/Ar=0.15) at above 270°C results from phase precipitation of SbN. Experimental results reveal that the temperature of crystallization to face-centered cubic (fcc) significantly increases from below 100°C to 160–220°C with increasing the ratio of N2/Ar (in the range of 0–0.15) and crystal structure further transforms from fcc to hexagonal. At high flow rate ratio of N2/Ar (>0.15), hexagonal Te phase firstly appears at 160°C and then orthorhombic SbN appears at 290°C.