n型掺杂GaAs中重空穴的飞秒动力学

本文采用fs脉冲饱和吸收光谱技术研究了室温下Si掺杂GaAs在电子激发态处于费密面附近时重空穴的超快弛豫特性。测量到重空穴的热化时间约为300fs,与理论计算结果一致,表明重空穴-光学声子散射是主要的热化途径,并得到光学形变势常数d₀为31eV.     

十二烷基苯磺酸在掺杂态聚苯胺LB膜中的分子取向

本文利用偏振红外光谱,研究了十二烷基苯磺酸分子在掺杂态聚苯胺ＬＢ膜中的分子取向。计算结果表明,十二烷基苯磺酸分子的烷基链是与基底法线方向呈１７°角度排布的,由Ｘ射线小角衍射峰推算出,在ＬＢ膜的沉积方向上,十二烷基苯磺酸掺杂的聚苯胺分子的层间距为２９５ｎｍ。     

MII(C4H12N2)[B2P3O12(OH)] (MII = Co,Zn): Synthesis and Crystal Structure of Novel Open Framework Borophosphates

Two novel borophosphates, M^II(C₄H₁₂N₂)[B₂P₃O₁₂(OH)] (M^II = Co, Zn), exhibiting open frameworks, have been synthesized by hydrothermal reactions (T = 165 °C). The crystal structures of the isotypic compounds have been determined both at 293 K (orthorhombic, Ima2 (no. 46), Z = 4; M^II = Co: a = 12.4635(4) Å, b = 9.4021(4) Å, c = 11.4513(5) Å, V = 1341.90 ų, R₁ = 0.0202, wR₂ = 0.0452, 2225 observed reflections with I > 2σ(I); M^II = Zn: a = 12.4110(9) Å, b = 9.4550(5) Å, c = 11.4592(4) Å, V = 1344.69 ų, R₁ = 0.0621, wR₂ = 0.0926, 1497 observed reflections with I > 2σ(I)). Distorted CoO₆‐octahedra and ZnO₅‐square‐pyramids, respectively, share common oxygen‐corners with BO₄‐, PO₄‐ and (HO)PO₃‐tetrahedra. The tetrahedral groups are linked via common corners to form infinite loop‐branched borophosphate chains [B₂P₃O₁₂(OH)^4–]. The open framework of M^II‐coordination polyhedra and tetrahedral borophosphate chains contains a three‐dimensional system of interconnected structural channels running along [100], [011] and [011], respectively, which are occupied by di‐protonated piperazinium ions.     

Synthesis and Structures of Amino(triphenylgermyl) Boranes and Trihydro(triphenylgermyl) Borates

The B‐(triphenylgermyl)borazines 4 a and 4 b , the 1,2‐bis(dimethylamino)‐1,2‐bis(triphenylgermyl)‐diborane(4), 5 , and the (2,2,6,6‐tetramethylpiperidino)(triphenylgermyl)‐boranes 6 and 7 were prepared by allowing LiGePh₃ to react with the corresponding B‐bromoborazines and aminochloroboranes, respectively. BH₃ dissolved in thf readily adds to LiGePh₃ generating Li(H₃BGePh₃), 8 a , in thf solution. Addition of N‐bases to the solution of 8 a produced (tmen · thf)Li(H₃BGePh₃), 8 b , and dimeric (py)₂Li(H₃BGePh₃), 8 c . The borazine ring in 4 b is distorted into a boat shape. In 5 the NBGe planes are twisted against each other by 85°. Comparison with analogous (triphenylstannyl)boranes points to a more pronounced steric effect of the Ph₃Ge group over the Ph₃Sn group due to the shorter B–Ge bond. A fairly short B–Ge bond is found for the (triphenylgermyl)trihydroborates. The molecular structure of (Et₂O)₃LiGePh₃ shows compressed C–Ge–C bond angles. Its molecular parameters fit well into the series L_nLiEPh₃ (E = Si, Sn, Pb).     

Synthesis and Structures of some Trisorganylstannyl Boranes and Triorganylstannyl Borates [1]

New stannylboranes were prepared from tetramethylpiperidino dichloroborane or B‐bromo‐pentamethylborazine with lithium triorganylstannides LiSnR₃. Only double stannylation was possible with tmpBCl₂ and LiSnMe₃, while tmpBCl(SnPh₃) was obtained by employing LiSnPh₃. This chloride reacted with LiGePh₃ to the stannyl germyl borane tmpB(GePh₃)(SnPh₃). On the other hand, PhMeNBCl₂ and an excess of LiSnMe₃ gave the borate Li[B(NMePh)(SnMe₃)₃], which was isolated as a solvate with 4 molecules of THF. The compound is present in the solid state as a solvent separated ion pair. The borate Li(H₃BSnMe₃) · 2 THF is dimeric in the solid state. Dimerization occurs via two single Li–H–B bridges and a Li–H(B)–Li bridge. The B–Sn bonds in the borates are practically of the same lengths as those in the boranes. In solution all BH bonds of this trihydridoborate are equivalent.     

硼协同掺杂金刚石单晶的高温高压合成

金刚石是一种具有优异性能的极限性超硬多功能材料。人工合成的金刚石可通过掺杂的方式使其具有各种独特的性质。掺硼金刚石兼具p型半导体的导电特性和金刚石自身优良的物理和化学性能,在国防、医疗、勘探、科研等领域具有极高的应用价值。本文基于本课题组高温高压(HPHT)法合成的系列掺硼金刚石以及硼协同掺杂金刚石单晶,进行了硼掺杂金刚石、硼氢协同掺杂金刚石以及硼氮协同掺杂金刚石的合成和性能特征等方面的研究。通过表征合成样品在光学、电学方面的性能,探讨了不同掺杂添加剂对合成金刚石性能的影响,为合成高性能的半导体金刚石提供了思路。     

纳米金刚石的结构、光学性能和热稳定性研究

纳米金刚石兼具纳米材料和金刚石的双重特性,呈现出与微米金刚石、块体金刚石截然不同的特点。本文以不同尺寸金刚石样品为研究对象,采用扫描电镜、X射线衍射、光谱学、热重分析技术对其结构、光学性能和热稳定性进行研究。结果显示样品尺寸分别为300 μm、30 μm和100 nm,大尺寸样品结晶质量较好,富含孤氮杂质,为Ⅰb型金刚石。纳米金刚石样品结晶较差,含有少量石墨残留,并含有H₂O、N—H和C—H键,说明其表面存在诸多有机活性基团。大尺寸金刚石样品存在中性和带负电荷的氮空位缺陷,产生较强荧光,而纳米金刚石由于存在诸多的有机基团和表面缺陷,形成非辐射中心,导致荧光猝灭。大尺寸样品在300~525 nm具有较强吸收,而纳米金刚石样品在紫外-可见-近红外整个区域均呈现出较强吸收,透过率显著较低。随着颗粒尺寸的减小,金刚石的起始氧化温度逐渐下降,氧化速率降低,因此大颗粒尺寸金刚石样品具有更好的热稳定性。     

单根Sb掺杂ZnO微米线非平衡电桥式气敏传感器的制作与性能

通过使用化学气相沉积法,成功制备出超长、大尺寸的Sb掺杂ZnO微米线.基于非平衡电桥原理,利用单根Sb掺杂ZnO微米线作为非平衡电桥的一个桥臂,制作出了可以在室温环境下工作的气敏传感器原型器件.结果表明:室温下测得该传感器对20,50,100和200 ppm(1 ppm=10^-6)不同浓度的丙酮及乙醇气体的响应-恢复曲线均呈现为矩形形状,在空气及被测气体中均有稳定的电流值,并随着探测气体浓度的增大,器件的响应值也在逐渐增加.此外,还发现器件对丙酮气体具有更好的选择性,当丙酮气体浓度为200 ppm时,该传感器的响应时间为0.2 s,恢复时间为0.3 s,响应度高达243%.通过与普通电导式气敏传感器对比发现,采用这种非平衡电桥结构传感器可以明显地提高响应度,使响应和恢复时间更快.此外,还研究了器件的气体探测机理.     

Different substitutions lead to differences in the transport and recombination properties of group V doped SiCNTs

Silicon carbide nanotubes (SiCNTs) has attractive application prospects in the field of micro-nanodevices. Based on first-principle, we find that a shallow and a deep impurity levels appearing when a group-V element replaces a C, while only one deep impurity level appears when a group-V replaces a Si. This indicates that different electronic properties will be generated when group-V replace different sites of SiCNTs. Further numerical simulation results show that when dopant replaces C, the conductivity is about an order of magnitude higher than dopant replaces Si, and the conductivity increase with increasing temperature; the non-equilibrium minority carrier lifetime decrease with increasing temperature, when group-V replace the C, they are strong n-type, when replace the Si, they are in weak n-type and strong p-type. These results will help reveal the doping mechanism of SiC nanomaterials and the selection of dopants, and provide a theoretical basis for the preparation of micro-nanodevices.     

CuInS2量子点敏化ZnO基光阳极的制备与性能研究

采用两步法在导电玻璃(FTO)基板上制备纯氧化锌(ZnO)纳米棒和钇掺杂的氧化锌(ZnO∶Y)纳米棒,采用连续离子层吸附反应法(SILAR)在所制备的ZnO及ZnO∶Y纳米棒上沉积CuInS₂量子点制备ZnO/CuInS₂和ZnO∶Y/CuInS₂光阳极。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、电子探针能谱仪(EDS)、紫外-可见分光光度计(UV-Vis)、电流密度-电压(J-V)曲线等技术手段对不同光阳极样品的晶相结构、微观形貌、化学组成、光吸收性能和太阳电池性能进行了表征。实验结果表明:所制备的ZnO纳米棒和ZnO∶Y纳米棒为六方纤锌矿结构。CuInS₂量子点敏化的ZnO纳米棒薄膜的光学带隙从3.22 eV减小为2.98 eV。CuInS₂量子点敏化ZnO∶Y太阳能电池的短路电流密度和光电转换效率比未掺杂的ZnO纳米棒组装的太阳能电池分别提高了6.5%和50.4%。