Hexagonal AlN Layers Grown on Sulfided Si(100) Substrate

We have studied the influence of sulfide passivation on the initial stages of aluminum nitride (AlN)-layer nucleation and growth by hydride vapor-phase epitaxy (HVPE) on (100)-oriented single-crystalline silicon substrates. It is established that the substrate pretreatment in (NH₄)₂S aqueous solution leads to the columnar nucleation of hexagonal AlN crystals of two modifications rotated by 30° relative to each other. Based on the sulfide treatment, a simple method of oxide removal from and preparation of Si(100) substrate surface is developed that can be used for the epitaxial growth of group-III nitride layers.     

Asymmetry of the Defect Structure of Semipolar GaN Grown on Si(001)

The defect structure of a thick (~15 μm) semipolar gallium nitride (GaN) layer grown by hydride–chloride vapor phase epitaxy on a Si(001) substrate with buffer layers has been studied by transmission electron microscopy. The asymmetry of the defect structure of GaN epilayer has been revealed and analyzed. The influence of this asymmetry on the rate of decrease in the density of threading dislocations in the growing epitaxial layer is discussed.

     

Hydride Vapor-Phase Epitaxy of a Semipolar AlN(10$$bar {1}$$2) Layer on a Nanostructured Si(100) Substrate

Technical Physics Letters - We propose a method for the synthesis of hexagonal AlN layer on Si(100) substrate with a V-groove nanostructured surface where the angle between the sloped nanoridge...     

Epitaxy of GaN(0001) and GaN(10 $$\bar {1}$$ 1) Layers on Si(100) Substrate

Technical Physics Letters - Two different approaches to epitaxy of 4-μm-thick layers of polar GaN(0001) and semipolar GaN(10 $$\bar {1}$$ 1) on a V-shaped nanostructured Si(100) substrate with...     

不同射频溅射功率下直接制备Ca_2Si薄膜(英文)

磁控溅射系统在恒定Ar气压和Ar气流流量下,使用不同射频溅射功率在Si(100)衬底上分别沉积Ca薄膜;随后,800℃真空退火1 h.立方相的Ca2Si薄膜首次、单独、直接生长在Si(100)衬底上.实验结果指出,在多相共生的Ca-Si化合物中,沉积Ca薄膜时的射频溅射功率影响了立方相Ca2Si薄膜的质量;最优化的溅射功率是85 W.另外,退火温度为800℃时,有利于单一相Ca2Si的独立生长.并且,退火时间也是关键因素.     

Si（100）预结构基底对Si雕塑薄膜三维模拟生长的影响

建立一个雕塑薄膜三维生长的蒙特卡罗模型,模拟在PVD方法下Si在Si（100）基底上沉积的生长,考虑周期性排列预结构基底的阴影效应,模拟不同预结构单元宽度、间距及不同入射角度下斜柱状雕塑薄膜的三维形貌。结果表明,在入射角和宽度一定时,存在一个最佳间宽比值使得薄膜表面粗糙度最小;当宽度大于一定数值,粗糙度随间宽比值增大而...     

Thermal Properties of GaN Films Grown on Si Substrates

GaN films grown on Si substrates by molecular beam epitaxy with different nitridation times have been investigated. The GaN/Si structural and optical properties were evaluated by transmission electron microscopy, X-ray diffraction, atomic force microscopy, and photoluminescence. The effective thermal conductivity of the GaN/Si system was obtained using the photoacoustic technique, and from these results the nitridation time dependence of the interface thermal conductivity (η) can be evaluated using a two-layer model. An optimal nitridation time for which the GaN crystal quality can be improved was obtained. The variation of the parameter η for different nitridation times can be related to the interface phonon scattering process by the presence of disorder at the GaN/Si interface.     

Si(111)衬底上六方YMnO3薄膜的制备与铁电性质

采用化学溶液法在Si(111)衬底上制备了YMnO3薄膜.XRD结果表明,所制备的薄膜为六方纯相YMnO3,且具有部分择优取向生长.以Pt为顶电极,测试了YMnO3薄膜的电滞回线,结果表明,所制备的YMnO3薄膜具有良好的铁电性质.     

Properties of ZnO Thin Films Grown on Si (100) Substrates by Pulsed Laser Deposition

ZnO thin films were grown on Si (100) substrates by pulsed laser deposition using a ZnO target.The substrate temperature was varied in the range of room temperature to 800 ℃,and the oxygen partial pressure of 0.1333 Pa (1 m Torr) to 1333 Pa (10 Torr).The properties of the resulting films were investigated by photoluminescence (PL),grazing incidence X-ray diffraction (GIXRD),X-ray photoelectron spectroscopy (XPS),and field emission scanning electron microscopy (FESEM).Based on the ultraviolet (UV,～380 nm) to...     

阳极氧化铝作缓冲层的Si基GaN生长

尝试了Si基上生长GaN外延层的一种新的缓冲层材料一阳极氧化铝，在Si（111）衬底上电子束蒸发铝膜，经阳极氧化后放入MOCVD系统中退火，然后进行GaN外延生长，对材料的微结构和电学性质进行了测量和分析，并将得到的GaN材料制备成光导型的紫外光电探测器，器件在330－380nm紫外光区域有明显的响应，最后响应度为3．5A／W（5V偏压）。     

Si衬底上横向外延GaN材料的微结构和光学性质的研究

用氢化物气相外延 (HVPE)方法在Si(III)衬底上成功横向外延生长出晶体质量较好的GaN薄膜材料。透射电子显微镜 (TEM )的研究结果表明 ,横向外延区域GaN的位错密度明显减小。由于SiO2 掩膜腐蚀角的不同 (分别为 90°和 6 6°) ,导致了横向外延GaN材料一些独特的微观形貌。微区拉曼光谱由数百条拉曼散射曲线组成 ,每一条曲线有三个振动模 ,分别对应Si振动模式 (5 2 0cm- 1) ,E2 模式 (5 6 6cm- 1)和E1(LO)模式(732cm- 1)。在垂直条纹方向 ,峰位和峰宽没有明显的变化 ,而峰强约 5 μm会发生周期性变化     

Si基GaN紫外光探测器

报道了以Si(111)为衬底的GaN光导型紫钙探测器的制备及其光电流性质,探测器的光谱响应表明,这种GaN探测器在紫外波段250－360nm有近于平坦的光电流响应,36nm附近陡峭的截止边,在357nm波长处,测得5V偏压下的响应度高达6．9A／W。响应度随外加偏压的增加而增加,5V时达到饱和,通过拟合光电流响应随入射光调制频率的变化关系,得到GaN探测器的响应时间为4．8ms。     

脉冲激光沉积法在Si(111)衬底上生长高c轴取向LiNbO3薄膜

在氧压20Pa,衬底温度600℃,靶材与衬底距离4cm的最优化条件下,利用脉冲激光沉积(PLD)技术首次在无诱导电压和任何缓冲层的情况下,在单晶Si(111)衬底上生长具有优良结晶品质和高c轴取向的LiNbO3晶体薄膜.利用X射线衍射(XRD)、扫描电子显微镜(SEM)和原子力显微镜(AFM)对LiNbO3薄膜的结晶品质,择优取向性以及表面形貌进行了系统的分析.结果表明生长出了具有优异晶体质量的c轴取向LiNbO3薄膜,表面光滑平整且无裂纹产生,表面粗糙度约4.8nm,有利于硅基光电子器件的制备和利用.     

Single Crystalline GaN Tiles Grown on Si (111) Substrates by Confined Lateral Guided Growth to Eliminate Wafer Bowing

A novel concept termed confined lateral guided growth (CLGG) has been demonstrated to prepare single crystalline GaN microtiles with a goal to create high crystalline quality and strain‐free GaN on large‐sized Si (111) substrates. Uniform array of hexagonal GaN tiles has been created with a diameter of larger than 30 μm for each tile. As revealed by the surface pits density of around 2 × 10⁸ cm⁻², the density of dislocations in these GaN tiles has been significantly reduced compared with that obtained typically from a GaN heteroepitaxy on Si (111). The strain in GaN tiles has been dramatically reduced to nearly zero. This approach offers a route to eliminate wafer‐bowing for growing high crystalline quality GaN on Si, especially when the substrate size scales to 12 in and beyond. The growth behavior and mechanism within these confined growth masks are investigated by both finite element modeling and experimental studying, indicating that CLGG is dominated by gas phase diffusion.     

硅基GaN外延层的SIMS及XPS研究

采用真空反应法在硅基上制备出了GaN外延层。利用二次离子质谱和X射线光电子能谱对GaN外延层进行了深度剖析和表面分析。结果表明 ,外延层中Ga和N分布均匀 ;在表面处Ga发生了偏聚 ;外延层中还存在Si,O等杂质 ,但这些并未影响到GaN外延层的物相及发光性能。实验还表明 ,在外延生长前采用原位清洗可去除Si衬底表面的氧     

脉冲激光沉积法在GaN基片上制备c轴取向LiNbO_3薄膜

采用LiNbO3单晶靶材,以激光脉冲沉积方法在六方GaN(0001)基片上沉积制备c轴取向的LiNbO3薄膜。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和原子力显微镜(AFM)研究了沉积温度和氧气压强对生长的薄膜的相组成、外延关系、表面形貌、晶粒大小的影响。结果显示,沉积温度500℃、氧分压20~30 Pa是在GaN基片上生长c轴取向LiNbO3薄膜的最优生长条件。XRD分析表明,生长的LiNbO3薄膜具有两种晶畴结构,其外延关系分别为[1-100](0001)LiNbO3//[11-20](0001)GaN和[10-10](0001)LiNbO3//[-12-10](0001)GaN。SEM和AFM对薄膜的表面形貌表征表明,在最优生长条件下沉积的薄膜表面平整,致密度好。     

湿法腐蚀硅片并生长氧化锌纳米棒作为太阳能电池减反层研究

在硅基太阳能电池表面制备减反层可以有效降低硅表面的反射率, 提高吸收率, 从而提高硅基太阳能电池的光电转换效率。本研究利用四甲基氢氧化铵(Tetramethyl Ammonium Hydroxide TMAH)溶液对(100)单晶硅进行各向异性腐蚀, 在表面腐蚀出金字塔结构, 得到了最低为6%左右的反射率。然后采用水热法在该衬底生长氧化锌纳米棒, 得到了最低小于3%的反射率, 比单采用腐蚀或者ZnO纳米棒生长的硅表面的反射率更低。这种减反方法工艺简单、高效, 有望得到应用。