本文關(guān)鍵詞： 相變隨機(jī)存儲(chǔ)器 鍺銻碲相變材料 硅摻雜 數(shù)據(jù)保持時(shí)間 結(jié)晶激活能 光學(xué)帶隙 擦除寫入過程 開關(guān)特性　出處：《南京大學(xué)》2012年碩士論文　論文類型：學(xué)位論文

【摘要】：相變隨機(jī)存儲(chǔ)器(Phase-change Random Accessed Memory,PCRAM)是利用相變材料的可逆轉(zhuǎn)的相變來(lái)存儲(chǔ)信息的一種新型存儲(chǔ)器,被認(rèn)為是未來(lái)替代隨機(jī)存儲(chǔ)器(DRAM)的最優(yōu)選擇之一。本文以si摻雜鍺銻碲(GST)相變材料為中心。對(duì)電子束蒸發(fā)制備Si摻雜GST相變材料的熱致相變過程以及其光電特性進(jìn)行了研究,并利用PCRAM原型器件對(duì)相變材料的開關(guān)特性進(jìn)行了初步研究。 我們利用電子束蒸發(fā)系統(tǒng)和Si摻雜Ge2Sb2Te5靶材制備了Si-GST相變材料薄膜。利用實(shí)驗(yàn)方法研究了不同摻雜濃度的Si-GST相變材料的熱致相變過程。Si-GST薄膜方塊電阻在原位熱退火的過程中發(fā)生兩次明顯的下降,對(duì)應(yīng)兩次相變過程。通過與純GST薄膜的熱致相變的過程的對(duì)比,可以看出：Si摻雜在增大了薄膜晶態(tài)方塊電阻的同時(shí)維持了晶態(tài)非晶態(tài)之間必需的“開關(guān)比”。計(jì)算了不同摻雜濃度Si-GST薄膜的結(jié)晶激活能,Si原子摩爾比分別為4.76at.%、13.0at.%和16.7at.%的Si-GST薄膜估算其結(jié)晶激活能分別為：3.51eV、4.05eV和4.23eV。利用原位恒溫退火方法對(duì)不同摻雜濃度Si-GST薄膜進(jìn)行研究,通過外推法,推算出在80℃時(shí)不同Si-GST薄膜的數(shù)據(jù)保持時(shí)間均能達(dá)到十年(3×108s)以上。 利用分光光度計(jì)對(duì)不同摻雜濃度的Si-GST薄膜的光學(xué)性質(zhì)進(jìn)行了研究,確定了它們的吸收系數(shù),結(jié)合公式擬合得出了不同摻雜比例Si-GST薄膜在晶態(tài)和非晶態(tài)時(shí)的光學(xué)帶隙。結(jié)果表明,Si摻雜增大了GST225薄膜的光學(xué)帶隙,分別為非晶態(tài)下的約0.85eV和晶態(tài)下的最低0.51eV。Si-GST薄膜的晶態(tài)光學(xué)帶隙隨著摻雜濃度的增大而線性增大；而非晶態(tài)的Si-GST薄膜的光學(xué)帶隙在不同的摻雜濃度下基本保持在0.85eV附近,在誤差范圍內(nèi)基本相同。 制作了PCRAM存儲(chǔ)單元原型器件,對(duì)相變材料開關(guān)特性進(jìn)行了初步研究。發(fā)現(xiàn),相變存儲(chǔ)單元均能完成寫入和擦除的過程。純GST有源層器件的平均閾值電壓為1.6V,Si摻雜GST有源層(9.09at.%)平均閾值電壓為2.6V。Si摻雜使器件的平均閾值電壓有所提高,增大了有源層晶態(tài)電阻,降低了擦寫電流,有效降低了工作功率。對(duì)不同有源層厚度的器件研究表明,發(fā)現(xiàn)平均閾值電壓與樣品厚度成正比,對(duì)于同一組分的相變材料,不同有源層厚度的器件平均閾值場(chǎng)強(qiáng)基本保持一致。
[Abstract]:Phase-change Random Accessed memory (PCRAM) is a new type of memory that uses the reversible phase transition of phase change materials to store information. It is considered as one of the best alternatives to random access memory (RAM) in the future. In this paper, the thermal phase transition process and its photoelectric properties of Si-doped GST phase change materials prepared by electron beam evaporation have been studied, focusing on si doped antimony germanium tellurium phase change materials. The switching characteristics of phase change materials are studied by using PCRAM prototype device. We have prepared Si-GST phase change material thin films by electron beam evaporation system and Si doped Ge2Sb2Te5 target. The thermal induced phase transition process of Si-GST phase change materials with different doping concentration. Si-GST thin film sheet resistance in situ thermal degradation has been studied by experimental method. There have been two distinct drops in the course of the fire, By comparing with the thermo-induced phase transition of pure GST thin films, It can be seen that the ratio of Si atoms to Si atoms in Si-GST films with different doping concentration is 4.76at.130at.% and 16.7 at.%, respectively, while increasing the square resistance of crystalline state while maintaining the "switching ratio" between crystalline and amorphous states. The activation energies of Si atoms are 4.76at.% and 16.7at.%, respectively. The crystallization activation energies of Si-GST thin films were estimated to be 4.05 EV and 4.23 EV, respectively. In situ constant temperature annealing method was used to study Si-GST films with different doping concentrations. By extrapolation, the data retention time of different Si-GST films at 80 鈩，

本文編號(hào)：1538906