Study On Doping Modification Of Sb And Ge₂Te Phase Change Films

Phase change memory(PCM)has been considered as one of the most promising non-volatile memories in the next generation due to its low power consumption,high density,and good compatibility.As the core layer of PCM,phase change material has deficiencies in the crystallization speed and thermal stability.For example,traditional Ge-Sb-Te sulfur-based compounds(Ge₂Sb₂Te₅)is widely used for the research of PCM,while poor thermal stability and high melting point have limited its further commercialization.In recent years,many new phase change materials have been proposed,including Sb and Ge₂Te phase change thin films.Sb films have attracted widespread attention due to its ultra-fast crystallization speeds,while Sb films have poor thermal stability due to explosive crystallization mechanism.Ge₂Te films have a larger switching ratio and higher thermal stability,while the crystallization speed needs to be improved.In this paper,the method of doping modification was proposed to address the issues mentioned above of Sb and Ge₂Te films,and it was studied systematically to optimize the thermal stability and power consumption performance for PCM.The main results of this paper are as follows:1.Study on the properties of Sb-VO₂ phase change film.After doping with VO₂,the thermal stability of the Sb thin film was significantly improved,and the crystallization temperature and 10-year data retention temperature of(VO₂)₂₅Sb₇₅thin film reached 238°C and 145°C,respectively.The VO₂ grid frame restricts the growth of Sb grain,which makes the crystallization mechanism of the Sb thin film changes from the explosive crystallization to nucleation-dominated crystallization mechanism,and the thermal stability of thin film was improved.After the addition of VO₂,a large number of Sb-VO₂ grain boundaries appear,which increases the crystalline resistance of the film and beneficial to reduce power consumption.Both the crystalline and amorphous optical band gaps increase with increasing VO₂ content,which is conducive to reducing the threshold current.These results provide a material basis for constructing high-stability and high-speed phase-change memories based on simple components.2.Study on the properties of Zr-doped Ge₂Te phase change films.The results show that the crystallization temperature and 10-year data retention temperature of the doped(Ge₂Te)₈₀Zr₂₀ thin film can up to 334°C and 233°C,respectively,which is higher than that of pure Ge₂Te film(220°C and 108°C),indicating that the thermal stability is significantly improved,which is due to the formation of more stable Zr-Ge and Zr-Te bonds after Zr doping.From the perspective of thermal stability and crystallization speed of the phase change thin films,the component of(Ge₂Te)₈₈Zr₁₂thin films was optimized,its optical band gap is larger than that of Ge₂Te film,and easy to form trap states in the amorphous state,which is beneficial to complete the transition from amorphous to crystalline.