Preparation And Characterization Of Chalcogenide Phase-change-memory Semiconductor Materials

Since chalcogenide alloy films was used in the phase change data storage,the phase-change memory technology appeared,and developed in the 1980s rapidly.In a sense,the advantages and disadvantages of phase-change memory devices depend on the performance of phase change materials.So research and development performance of phase change materials has become the core of phase-change memory technology.And chalcogenide compounds is the important group of phase-change memory material.Particularly,the nano-crystalline binary(â…¤-â…¥) and ternary (Ge-â…¤-â…¥) chalcogenide semiconductors have higher specific surface area, higher activeness in chemical properties,and special photoelectric properties which cause the widespread interest in scientific community.In this paper,Sb-Se,Sb-Te and Ge-Sb-Te series of phase change materials were synthesized by solid-state method,the synthesis conditions were studied,still the morphology and structure were analysed.The main study contents and results include:(1) The ratios of elements and preparation parameters were designed and optimized.The optimum preparation temperature of Sb-Se materials was 700℃,Sb-Te materials was 750℃,and the Ge-Sb-Te materials was 1100℃;(2) The Sb-Se group materials were analysed,which indicated that the element ratio,sinter point,and cooling down method could influence the preparation of the material.And according to the result,the stability of the out growth could be obtained as follows,Sb₂Se₃(air cooling)â†'Sb₂Se₃ (furnace cooling)â†'SbSeâ†'Sb₁Se₄â†'Sb₄Se₁;(3) The Sb-Te group materials were analysed.The product was 65-3678 Sb₂Se₃ of orthorhombic phase and R-3m space group.The diffraction peaks was stronger,as the ratio was close to 2:3.The product was Sb₇Te₁ of orthorhombic phase and P-63m space group,when the ratio was Sb₉Te₁;(4) The crystal cell structure of Sb₂Se₃ was still a typical orthorhombic phase of R3m and did not change,even GeTe was doped in.The XRD patterns went to the right in minor point,as follows Ge₁Sb₄Te₇â†'GeSb₂Te₄â†'Ge₂Sb₂Te₅.And the thermal stability increased gradually.