a-SiH 热处理过程中纳米硅粒尺寸的控制(英文)

报道了控制热处理过程中含氢非晶硅中纳米硅颗粒大小的一种新方法。用喇曼散射、X射线衍射和计算机模拟,发现在非晶硅中所形成的纳米硅颗粒的大小,随着热退火过程中升温速率的变化而变化。在退火过程中,若非晶硅薄膜升温速率较高(～100℃/s),则所形成纳米硅粒的大小在1.6～15nm;若非晶硅薄膜升温速率较低(～1℃/s),则纳米硅粒大小在23～46nm。根据晶体生长理论,讨论了升温速率的高低与所形成的纳米硅颗粒大小的关系。     

利用热退火法从非晶硅薄膜中生长纳米硅粒

报道了一种从氢化非晶硅薄膜中生长纳米硅粒的方法.氢化非晶硅薄膜经过不同条件的热退火处理后,用拉曼散射和X射线衍射技术对样品进行了分析.实验结果表明:在快速升温条件下所形成的nc-Si在薄膜中的分布是随机均匀的,直径在1.6～15 nm范围内,硅粒大小随退火过程中升温快慢而变化.     

氢化非晶硅薄膜退火形成的纳米硅粒

报道了氢化非晶硅薄膜在600～620℃温度下快速退火10s可以形成纳米晶硅,其喇曼散射表明,在所形成的纳米晶硅在薄膜中分布是随机的,其直径在1.6～15nm以内.并且在强光照射下观察了纳米晶硅在薄膜中的结晶和生长情况.     

利用快速退火法控制非晶硅薄膜中纳米硅粒尺寸

报道了利用快速退火法控制膜中纳米硅粒大小的方法,讨论了升温快慢与所形成的纳米硅粒大小的关系.     

a-Si:H热处理过程中形成的纳米硅粒及其光致发光

报道了氢化非晶硅薄膜在600～620℃温度下快速退火10 s可以形成纳米晶硅,其拉曼散射表明,所形成的纳米晶硅在薄膜中的分布是随机的,其直径在1.6～15 nm内.根据晶体生长理论和计算机模拟,讨论了升温快慢与所形成纳米硅颗粒大小之间的关系,并且在强光照射下观察了纳米晶硅在薄膜中的结晶和生长情况.经退火形成的nc-Si可见光辐射较弱,不能检测到它们的光致发光,但用氢氟酸腐蚀钝化后则可检测到较强的红PL,并且钝化后的nc-Si在空气中暴露一定时间后,其辐射光波长产生了蓝移.就表面钝化和量子限制对可见光辐射的重要性作了讨论.     

用硅离子注入SiO2层方法制备的纳米硅的光学性质

报道了用硅离子注入热氧化生长的SiO2 层后热退火的方法制备纳米硅样品,并在室温下测量了样品的光致发光谱及其退火温度的关系.实验结果表明,在800℃以下退火的样品的发光是由于离子注入而引入SiO2 层的缺陷发光.在900℃以上退火,才观察到纳米硅的发生,在1100℃下退火,纳米硅发光达到最强.纳米硅的发光峰随退火温度升高而红移呈量子尺寸效应.在直角散射配置下,首次观察到纳米硅的特征拉曼散射峰,进一步证实了光致发光谱的结果.     

高温快速热处理对硅中热施主的影响

研究了不同气氛(N2 、O2 、Ar)下高温快速热处理(RTP)对热施主形成和消除特性的影响.研究发现无论在何种气氛下进行高温RTP ,对热施主的形成均无影响.扩展电阻的分析结果表明,热施主在硅片纵向的分布是均匀的.根据高温RTP后硅片的空位特征,认为点缺陷对热施主的形成特性无影响.同时研究了高温RTP预处理对热施主消除特性的影响,发现氧气和氩气高温RTP的样品其生成的热施主经过6 5 0℃退火即可消除,和普通的热施主消除特性相同.而N2 气氛下高温RTP的样品,6 5 0℃退火后仍有部分施主存在,经95 0℃退火才能彻底消除,这可能是由于RTP处理中发生氮的内扩散     

高温快速热处理对硅中热施主的影响

研究了不同气氛(N2、O2、Ar)下高温快速热处理(RTP)对热施主形成和消除特性的影响.研究发现无论在何种气氛下进行高温RTP,对热施主的形成均无影响.扩展电阻的分析结果表明,热施主在硅片纵向的分布是均匀的.根据高温RTP后硅片的空位特征,认为点缺陷对热施主的形成特性无影响.同时研究了高温RTP预处理对热施主消除特性的影响,发现氧气和氩气高温RTP的样品其生成的热施主经过650℃退火即可消除,和普通的热施主消除特性相同.而N2气氛下高温RTP的样品,650℃退火后仍有部分施主存在,经950℃退火才能彻底消除,这可能是由于RTP处理中发生氮的内扩散,在后续热处理中形成氮氧复合体浅施主中心所致.     

激光能量对沉积纳米Si薄膜晶粒尺寸的影响

为了制备纳米硅薄膜,采用脉冲激光沉积系统,保持靶材和衬底间距不变,在不同激光能量条件下,得到一系列纳米Si薄膜。利用喇曼散射光谱和X射线衍射谱对晶粒尺寸进行了计算和分析,取得了几组数据。结果表明,改变脉冲激光能量时,纳米Si晶粒平均尺寸均随能量的增强先增大后减小;在单脉冲能量为300mJ时制备的纳米Si晶粒平均尺寸最大,为8.58nm。这一结果对纳米硅薄膜制备的研究有积极意义。     

Au纳米颗粒的形状和尺寸对表面等离子体的影响

通过调控Au纳米颗粒的形状和尺寸,研究了Au纳米颗粒的形状和尺寸与表面等离子体之间的关系。通过直流磁控溅射的方法在外延片上溅射Au薄膜,并采用快速热退火和常规热退火两种方式对其进行热退火,制备出Au纳米颗粒。使用不同热退火方式、不同热退火温度及不同Au薄膜厚度来改变Au纳米颗粒的形状和尺寸,并对Au纳米颗粒的表面形貌及它的消光谱进行了分析,对比了不同形貌的Au纳米颗粒对表面等离子体共振特性的影响。实验结果表明,使用普通热退火制备的Au纳米颗粒形状接近球体,而使用快速热退火得到的Au纳米颗粒的形状更接近棒体;随着热退火温度的升高,表面等离子体的共振波长发生红移;随着Au薄膜厚度的增加,表面等离子体的共振波长也发生红移。     

Size Control of Nanoscale Silicon Particles Formed in Thermally Annealed A- Si: H Films and Its Photoluminescence

A method to control the size of nanoscale silicon grown in thermally annealed hydrogenated amorphous silicon (a-Si : H) films is reported. Using the characterizing techniques of micro-Raman scattering,X-ray diffraction and computer simulation, it is found that the sizes of the formed silicon particles change with the temperature rising rate in thermally annealing the a-Si : H films. When the a-Si: H films have been annealed with high rising rate( ～ 100 C/s), the sizes of nanoscale silicon particles are in the range of 1.6～ 15nm. On the other hand, if the a-Si: H films have been annealed with low temperature rising rate(～1 C/s),the sizes of nanoscale silicon particles are in the range of 23～46 nm. Based on the theory of crystal nucleation and growth, the effect of temperature rising rate on the sizes of the formed silicon particles is discussed. Under high power laser irradiation, in situ nanocrystallization and subsequent nc-Si clusters are small enough for visible light emission, authors have not detected any visible photoluminescence(PL) from these nc-Si clusters before surface passivation. After electrochemical oxidization in hydrofluoric acid, however, intense red PL has been detected. Cyclic hydrofluoric oxidization and air exposure can cause subsequent blue shift in the red emission. The importance of surface passivation and quantum confinement in the visible emissions has been discussed.     

Size Control of Nanoscale Silicon Particles Formed in Thermally Annealed A-Si∶H Films and Its Photoluminescence

A method to control the si ze of nanoscale silicon grown in thermally annealed hydrogenated amorphous silico n (a-Si∶H) films is reported. Using the characterizing techniques of micro-Ra man scattering, X-ray diffraction and computer simulation, it is found that the sizes of the formed silicon particles change with the temperature rising rate i n thermally annealing the a-Si∶H films. When the a-Si∶H films have been anne aled with high rising rate( ~100 ℃/s), the sizes of nanoscale silicon particle s are in the range of 1.6~15 nm. On the other hand, if the a-Si∶H films have been annealed with low temperature rising rate(~1 ℃/s), the sizes of nanoscale silicon particles are in the range of 23~46 nm. Based on the theory of crystal nucleation and growth, the effect of temperature rising rate on the sizes of th e formed silicon particles is discussed. Under high power laser irradiation, in situ nanocrystallization and subsequent nc-Si clusters are small enough for vis ible light emission, authors have not detected any visible photoluminescence(PL) from these nc-Si clusters before surface passivation. After electrochemical ox idization in hydrofluoric acid, however, intense red PL has been detected. Cycli c hydrofluoric oxidization and air exposure can cause subsequent blue shift in t he red emission. The importance of surface passivation and quantum confinement i n the visible emissions has been discussed.     

Identification of Nucleation Center Sites in Thermally Annealed Hydrogenated Amorphous Silicon

Utilizing the concepts of a critical crystallite size and local film inhomogeneity, it is shown that nucleation in thermally annealed hydrogenated amorphous silicon occurs in the more well ordered spatial regions in the network, which are defined by the initial inhomogeneous H distributions in the as‐grown films. Although the film H evolves very early during annealing, the local film order is largely retained in the still amorphous films even after the vast majority of the H is evolved, and the more well ordered regions which are the nucleation center sites for crystallization are those spatial regions which do not initially contain clustered H, as probed by H NMR spectroscopy. The sizes of these better ordered regions relative to a critical crystallite size determine the film incubation times (the time before the onset of crystallization). Changes in film short range order upon H evolution, and the presence of microvoid type structures in the as grown films play no role in the crystallization process. While the creation of dangling bonds upon H evolution may play a role in the actual phase transformation itself, the film defect densities measured just prior to the onset of crystallization exhibit no trends which can be correlated with the film incubation times.     

石墨上多晶硅薄膜的制备及择优取向的调控

利用磁控溅射在石墨衬底上制备了非晶硅薄膜,并使用快速热退火对薄膜进行了晶化处理。XRD分析表明,直接溅射沉积在石墨衬底上的硅薄膜经过快速热退火后具有高度的(220)择优取向。通过在硅薄膜和石墨衬底界面处引入一定厚度的ZnO中间层,晶化后的多晶硅薄膜择优取向实现了从(220)向(400)的转变,从而非常有利于将成熟的制绒工艺应用于该材料体系的电池制备过程中。对于择优取向的转变提出了解释,认为Si(100)面和ZnO(001)面晶格匹配是主要原因。喇曼分析表明ZnO中间层的引入提高了多晶硅薄膜的晶体质量。     

GaN薄膜的微区Raman散射光谱

报道了低压 MOCVD生长的同一 Ga N薄膜不同位置的微区 Raman散射光谱 .观测到了微区结构不完整对 Raman谱的影响 .通过 X射线衍射分析 ,证实了该样品晶体质量是不均匀的 ,而且微结构缺陷的存在是导致回摆曲线展宽的主要原因 .结合 Hall测量结果 ,对 Ga N薄膜的 Al( L O)模式的移动进行了电声子相互作用分析 ,认为 A1 ( LO)模式的移动可能与电声子相互作用无关 ,而是受内部应力分布不均匀的影响所致 .