SiGe合金半导体中自间隙缺陷和两种碳相关缺陷的计算研究

采用从头计算(ab initio)的方法对比研究了Si1-xGex合金半导体材料中W缺陷、CiCs缺陷和CiOi缺陷的性质.在S1-xGex合金中,Ge原子不能与缺陷核心的C原子和O原子直接成键,但可能与W缺陷核心的间隙Si原子相连.在含CiOi缺陷的晶胞中,Ge原子倾向于取代沿[110]伸长方向的Si原子.随着合金中Ge含量的升高,W缺陷的形成能不断增加,结构稳定性逐渐降低.与w缺陷不同的是,CiCs缺陷和CiOi缺陷在不同Ge含量的Si1-xGex合金中形成能变化较小,变化幅度在0.15 eV以内,理论研究结果与前人的实验结果相吻合.     

Si1-yCy合金薄膜中替位式C组分随生长温度的变化

用化学气相淀积方法,以乙烯为碳源、硅烷为硅源,在si(100)衬底上外延生长了替位式C组分达1.22%的Si1-yCy合金薄膜,研究表明:处于替位式格点位置的C原子与Si原子成键,形成Si-C局域振动模;随着生长温度的降低,更多具有较低迁移率的C原子占据替位式格点,导致合金薄膜中的替位式C组分增加、间隙式缺陷减少,薄膜的晶体质量得到有效提高;相应地薄膜承受的张应力增大,外延层中Si(TO)声子模发生蓝移.     

用于应变Si外延薄膜的SiC缓冲层的生长

用化学气相沉积方法对Si(111)衬底进行碳化处理,继而生长SjC外延层和应变Si薄膜.结果表明:随着碳化温度的降低,SiC薄层与Si衬底界面处的空洞有逐渐变小的趋势;在1100℃进行碳化处理可以有效减少界面处的空洞,得到较平整的sic薄层,在此条件下外延生长了高质量的SiC薄膜.在该SiC薄膜上外延获得了具有单一晶向的应变sj薄膜,其霍尔迁移率明显高于相同掺杂浓度的体Si材料,电学性能得到了有效改善.     

Si衬底上3C-SiC异质外延应力的消除

利用低压化学气相沉积方法在N型Si衬底上异质外延生长3C-SiC薄膜,研究和分析了不同碳化工艺和生长工艺对3C-SiC外延层的影响;探讨了Si衬底3C-SiC异质外延应力的消除机理.通过台阶仪和XRD对不同工艺条件下的外延层质量进行分析,得到最佳工艺条件的碳化温度为1000 ℃,碳化时间为5 min,生长温度为1200 ℃,生长速度为4 μm/h.对最佳工艺条件下得到的外延层的台阶仪分析表明外延层弯曲度仅为5μm/45 mm;而外延层的XRD和AFM分析表明,3 μm厚度外延层SiC(111)半高宽为0.15°,表面粗糙度为15.4nm,表明外延层结晶质量良好.     

La_(1.1)Fe_(11.4)Si_(1.55)Ge_(0.05)合金的磁热效应

使用电弧熔炼法制备了La1.1Fe11.4Si1.55Ge0.05合金。研究了用少量的Ge替代Si后,La1.1Fe11.4Si1.55Ge0.05合金的磁性和磁热效应。粉末X射线衍射结果表明:在1273K真空退火处理10d后,合金La1.1Fe11.4Si1.55Ge0.05主相为NaZn13型立方结构,存在微量的α-Fe相。热磁曲线M-T与Arrott曲线表明:在居里温度Tc=205K处发生由铁磁性(TTc)转变为顺磁性(TTc)的二级磁相变。在磁场变化0～1.5T下,根据等温磁化曲线通过Maxwell关系式计算得出最大磁熵变-ΔSmmax=9J.kg-.1K-1。Ge替代Si后该合金在其居里温度Tc处-ΔSm-T曲线半高宽增大,使合金的相对制冷能力RCP(S)有所提高。     

Si衬底上SrMnO3缓冲层对La0.8Sr0.2MnO3薄膜择优取向生长的影响

利用磁控溅射方法在(100)Si衬底上首先生长SrMnO3(SMO)作为缓冲层，再沉积得到了(110)择优取向生长的La08Sr02Mn03(LsMO)薄膜。利用X射线衍射仪分析了SMO缓冲层的结构特征对LSMO薄膜择优取向生长的影响。结果表明：当沉积温度为600℃时，增加缓冲层SMO的厚度，LSMO薄膜的取向性变好；当缓冲层SMO厚度为45nm时，LSMO薄膜基本具有(110)取向生长的特征。进一步的工作证实：提高沉积温度，能够显著增加SMO缓冲层的晶粒大小，并减少LSMO薄膜择优取向生长所需的缓冲层厚度；当沉积温度为800℃时，由于类退火作用的存在，厚度为10nm的SMO缓冲层就可以实现LSMO薄膜择优取向的生长。     

Gd2O3-HfO2栅介质薄膜的外延制备及Ge-MOS电学特性分析

以Gd2O3-HfO2( GDH)固溶氧化物作为靶材,采用脉冲激光沉积技术(PLD)在Ge(100)衬底上制备了GDH高k栅介质外延薄膜,其外延生长方式为“cube-on-cube”,GDH薄膜与Ge(100)衬底的取向关系为(100)GDH∥(100)Ge和[110] GDH∥[110]Ge.通过反射式高能电子衍射(RHEED)技术研究了激光烧蚀能量和薄膜沉积温度对薄膜晶体结构的影响,分析了二者与薄膜的取向关系,激光烧蚀能量对薄膜取向影响更为显著.得到较优的GDH外延薄膜沉积工艺为:激光烧蚀能量为3 J·cm-2、薄膜的沉积温度为600℃.用磁控溅射制备了Au/Ti顶电极和Al背电极,其中圆形的Au/Ti电极通过掩膜方法获得,直径为50μm.采用Keithley 4200半导体测试仪对所制备Au/Ti/GDH/Ge/Al 堆栈结构的Ge-MOS原型电容器进行电学特性分析,测试条件为:I-E测试的电场强度0～6MV·cm-1,C-V测试的频率300 kHz～1 MHz,结果表明,厚度为5nm的GDH薄膜具备良好介电性能:k-28,EOT ～0.49 nm,适于22 nm及以下技术节点集成电路的应用.     

MnP_(1-x)M_x系列合金的磁热效应

研究了1∶1型MnP基系列合金MnP1-xMx(M=Si,Sb,Ge,Zn,Sn)(x=0,0.1)的结构及其磁热效应。室温X射线衍射表明该系列合金的主相结构均为正交MnP结构,空间群为Pnma。在用Ge,Sb,Zn,Sn作为替代元素的合金中存在少量第二相Mn5.64P3。磁性测量表明该系列合金MnP1-xMx(M=Si,Sb,Ge,Zn,Sn)(x=0,0.1)的存在由铁磁-顺磁的二级相变。其居里温度Tc分别为286,295,294,295,295K。通过磁化曲线计算了MnP1-xMx(M=Si,Sb,Ge,Zn,Sn)(x=0,0.1)合金的最大等温磁熵变-ΔSm,均在0.7～1.3J.kg-.1K-1之间。     

双缓冲层法在硅上外延生长GaN研究

利用金属有机物化学金相沉积MOCVD在Si(111)衬底上，以高温AlN和低温GaN为缓冲层生长的GaN薄膜，得到GaN(0002)和(10-12)的双晶X射线衍射(DCXRD)半高宽(FWHM)分别为721和840s。采用高分辨率DCXRD，扫描电子显微镜(SEM)分析。结果表明，以1040℃生长的AlN缓冲层能防止Ga与Si反应形成无定形的Si-Ga结构，是后续生长的“模板”。低温的GaN缓冲层可有效减低外延层的缺陷。DCXRD测得的FWHM为0．21，GaN峰强达7K。     

MBE法生长硅薄膜

以乙硅烷(Si_2H_6)为气体源,在Si(001)基底上均质外延生长了不掺杂硅薄膜。基底温度为533～1000℃,在此温区内均可获得单晶外延层。文章探讨了外延层生长速率、结晶度和杂质在晶体生长过程中的再分配问题。700℃制成的试样为 n     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.     

Quality of life of relatives of mental patients

Usage of quality of life of psychiatric patients' relatives as the parameter of estimation of the quality of psychiatric care is considered. By means of standard questionnaire elaborated by the authors as well as by means of both individual and group conversations the quality of life was analyzed in 40 relatives which lived together with psychiatric patients. Different spheres of their life and difficulties (financial, social-psychologic, production) were examined in families with such patients. The defects of psychiatric care that had direct influence on the quality of life of the psychiatric patients' relatives are outlined.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)