Baowei QIAO
,
Yunfeng LAI
,
Jie FENG
,
Yun LING
,
Yinyin LIN
,
TingAo TANG
,
Bingchu CAI
,
Bomy CHEN
材料科学技术（英文）
The amorphous Ge2Sb2Te5 film with stoichiometric compositions was deposited by co-sputtering of separate Ge, Sb, and Te targets on SiO2/Si (100) wafer in ultrahigh vacuum magnetron sputtering apparatus. The crystallization behavior of amorphous Ge2Sb2Te5 film was investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and differential scanning calorimetry (DSC). With an increase of annealing temperature, the amorphous Ge2Sb2Te5 film undergoes a two-step crystallization process that it first crystallizes in face-centered-cubic (fcc) crystal structure and finally fcc structure changes to hexagonal (hex) structure. Activation energy values of 3.636±0.137 and 1.579±0.005 eV correspond to the crystallization and structural transformation processes, respectively. From annealing temperature dependence of the film resistivity, it is determined that the first steep decrease of the resistivity corresponds to crystallization while the second one is primarily caused by structural transformation from "fcc" to ``hex" and growth of the crystal grains. Current-voltage (I-V) characteristics of the device with 40~nm-thick Ge2Sb2Te5 film show that the Ge2Sb2Te5 film with nanometer order thickness is still applicable for memory medium of nonvolatile phase change memory.
关键词:
Co-sputtering
,
null
,
null
,
null
,
null
Xing′ao LI
,
Zuli LIU
,
Kailun YAO
材料科学技术（英文）
Copper nitride thin film was deposited on glass substrates by reactive DC (direct current) magnetron sputtering at a 0.5 Pa N2 partial pressure and different substrate temperatures. The as-prepared film, characterized with X-Ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy measurements, showed a composed structure of Cu3N crystallites with anti-ReO3 structure and a slight oxidation of the resulted film. The crystal structure and growth rate of Cu3N films were affected strongly by substrate temperature. The preferred crystalline orientation of Cu3N films were (111) and (200) at RT, 100℃. These peaks decayed at 200℃ and 300℃ only Cu (111) peak was noticed. Growth of Cu3N films at 100℃ is the optimum substrate temperature for producing high-quality (111) Cu3N films. The deposition rate of Cu3N films estimated to be in range of 18–30 nm/min increased while the resistivity and the microhardness of Cu3N films decreased when the temperature of glass substrate increased.
关键词:
DC magnetron sputtering
,
氮化铜薄膜
,
电阻率
,
显微硬度
孙天鸣
,
董利民
,
王晨
,
郭文利
,
王莉
,
梁彤祥
新型炭材料
doi:10.1016/S1872-5805(13)60087-6
依据经典流体力学理论,建立了真实密度和孔隙率对炭素材料电阻率影响规律的模型.模型计算结果表明,真实密度对炭素材料的电阻率影响较小,偏差小于3％;开孔气孔率对电阻的影响大于闭孔气孔率,开孔气孔率增加40％时电阻率增加了250％,而相同幅度闭孔气孔率的增加引起电阻率的增加值只有25％.模型计算结果与实测值偏差小于2％,表明模型具有较好的精度.
关键词:
模型
,
炭材料
,
电阻
,
气孔率
李玉
,
于海鹏
,
戚大伟
,
程倩
,
王在山
低温物理学报
采用溶胶凝胶法通过较低温度、较短的烧结时间制备了单相的多晶钙钛矿Pr_(0.75)Na_(0.25)Mn_(1-x)Fe_xO_3(0≤x≤0.3),避免了Na元素的挥发及锰氧化物的析出,使Pr_(1-x)Na_xMnO_3中Na的最大掺入量由文献报道的0.19提高到0.25,样品单相性得到大幅度提高.系列样品的磁化强度、电阻率随温度的变化关系表明2%的Fe掺杂便能大大减弱低温电荷有序;在x≤0.05时系列样品磁化强度随Fe含量的增加而增加,电阻率随Fe含量的增加而下降,然后二者随Fe含量进一步增加均朝相反的趋势变化.用几何效应(Fe~(3+)的几何尺寸大小)和电子结构的影响两个方面的竞争解释这种现象.
关键词:
磁化强度
,
电阻率
,
锰氧化物
,
溶胶凝胶法
朱慧
,
王瑞
,
刘牧春
,
张恒华
上海金属
纯铝熔液通过插入新鲜树枝增加其氢含量,并采用减压凝固及密度法测量氢含量.应用电阻法测量纯铝铸件的电阻率,通过建立电阻率与氢含量的简单物理模型,结合实验所得结果,最后得到纯铝铸件电阻率与氢含量的关系式为:ρ=0.231 85ln 0.858 36/C2+0.858 36+0.540 22CH +2.886 86.
关键词:
纯铝
,
氢含量
,
电阻率
