Passive Q-Switching in a Flash-Lamp Pumped Nd∶YAG Laser with Ion-Implanted GaAs Wafer

A passive Q-switched flash-lamp-pumped Nd:YAG laser with the ion-implanted semi-insulating GaAs water is reported．The wafer is implanted with 400keV As~+ ions in the concentration of 10~(16)cm~(-2). Using GaAs wafer as an absorber and an output coupler．62ns pulse duration of single pulse is obtained.

掺硼nc-Si:H薄膜中纳米硅晶粒的择优生长

利用等离子体增强化学气相沉积（PECVD）生长的系列掺硼氢化纳米硅（nc-Si:H）薄膜中纳米硅晶粒（nanocrystalline silicon，简称nc-Si)有择优生长的趋势。用HRTEM、XRD、Ramam等方法研究掺硼nc-Si:H薄膜的微观结构时发现：掺硼nc-Si:H薄膜的XRD只有一个峰，峰位在2θ≈47°，晶面指数为（220），属于金刚石结构。用自由能密度与序参量的关系结合实验参数分析掺硼nc-Si:H薄膜择优生长的原因是：适当的电场作用引起序参量改变，导致薄膜在适当的自由能范围内nc-Si的晶面择优生长。随着掺硼浓度的增加，nc-Si:H薄膜的晶态率降低并逐步非晶化。nc-Si随射频功率密度的增大而长大，但晶态率降低。nc-Si随衬底温度升高而长大，晶态率提高。nc-Si随射频功率密度的增大而长大，晶态率增大的趋势平缓。但未发现掺硼浓度、稀释比、衬底温度、射频功率密度的变化引起薄膜中nc-Si晶面的择优生长。

用半导体可饱和吸收镜对掺钕晶体激光器进行被动调Q和锁模

较全面介绍了几种掺钕激光晶体的光学性质。就掺钕激光晶体主要的三个波长探讨了用一种新型的吸收体（半导体可饱和吸收镜）进行被动调Q和锁模。

掺杂nc-Si:H薄膜中纳米硅晶粒的择优生长

发现PECVD生长的系列掺杂氢化纳米硅（nc-Si:H）薄膜中纳米硅晶粒（nc-Si）有择优生长的趋势。用Raman、XRD、AFM、HRTEM等方法研究其微观结构时发现：掺磷的nc-Si:H薄膜XRD峰位的二倍衍射角约为33~°。掺硼nc-Si:H薄膜的XRD峰位的二倍衍射角约为47~°。用自由能密度与序参量的关系结合实验参数分析得到：较高的衬底温度引起序参量改变，使掺磷nc-Si:H薄膜中nc-Si的晶面择优生长。适当的电场作用引起序参量改变，导致掺硼nc-Si:H薄膜在一定的身由能密度范围内nc-Si的晶面择优生长。

Nonlinear Absorption Properties of nc-Si∶H Thin Films

于2010-11-23批量导入

(n)nc-Si:H/(p)c-Si异质结中载流子输运性质的研究

采用常规等离子体增强化学气相沉积工艺，以高H_2稀释的SiH_4作为反应气体源和PH_3作为磷原子的参杂剂，在p型(100)单晶硅C(p)c-Si)衬底上，成功地生长了施主掺杂型纳米硅膜C(n)nc-Si:H),进而制备了(n)nc-Si;H/(p)c-Si异质结，并在230-420K温度范围内实验研究了该异质结的I-V特性。结果表明，(n)nc-Si:H/(p)c-Si异质结为一典型的突变异质结构，具有良好的温度稳定性和整流特性。正向偏压下，该异质结的电流输运机理为复合－隧穿模型。当正向偏压V_F<0.8V时，电流输运过程由复合机理所支配；而当V_F>1.0V时由隧穿机理决定。反向偏压下，该异质结具有良好的反向击穿持性。

nc-Si/SiO_2多层薄膜的三阶非线性光学性质

于2010-11-23批量导入

掺杂nc-Si∶H膜的电导特性

于2010-11-23批量导入

测试温度对nc-Si:H膜光致发光特性的影响

利用常规等离了体化学气相沉积(PECVD)工艺制备了nc-Si:H膜,并对其光致发光(PL)特性从10～250K温度范围内进行了变温测量。实验结果指出，随着测试温度升高，PL峰值能量发生了54meV的红移，PL强度在T>80K后呈指数下降趋势。PL峰值能量的红移起因于带隙的收缩，而PL强度的减弱则是由于非辐射复合起了主导作用。

nc-Si:H/c-Si量子点二极管中的共振隧穿特性分析

采用常规PECVD工艺，在N型单晶硅(c-Si)衬底上沉积薄层纳米Si(nc-Si)膜，并进而制备了nc-Si:H/c-Si量子点二极管。在10～100K温度范围内实验研究了该结构的σ-V和I-V特性。结果指出，当反向偏压为-7～-9V时，无论在σ-V还是在I-V特性曲线上都观测到了近乎等间距的量子化台阶，此起因于在nc-Si:H膜中具有无序排布且粒径大小不一的Si微晶粒中，由于微晶粒中能级的量子化而导致的共振隧穿现象。如果进一步改进膜层生工艺，以制备出具有趋于有序排布、尺寸均匀和粒径更小的Si微晶粒的nc-Si:H膜，有可能实现更高温度范围内的共振隧穿。

量子阱激光二极管泵浦Nd:YLF固体激光器的调Q

于2010-11-23批量导入

Characterization of diphasic nc-Si/a-Si : H thin films and solar cells

Hydrogenated silicon films with diphasic structure have been prepared by using a new regime of plasma enhanced chemical vapor deposition (PECVD) in the region adjacent to the phase transition from amorphous to crystal. line state. The photoelectronic and microstructural properties of the films have been characterized by the constant photocurrent method (CPM), Raman scattering and nuclear magnetic resonance (NMR). In comparison with typical hydrogenated amorphous silicon (a-Si:H), these diphasic films with a crystalline fraction less than 0.3 show a similar optical absorption coefficient, lower deep-defect densities and higher stability upon light soaking. By using the diphasic nc-Si/a-Si films a p-i-n junction solar cell has been prepared With an initial efficiency of 8.51 % and a stabilized efficiency of 8.02 % on an area of 0.126 cm(2) (AM1.5, 100 mW/cm(2)).

Preparation and photoluminescence of nc-Si/SiO2 MQW

The deposition rate and refractive index for a-Si(amorphous silicon) and SiO2 grown by PECVD were studied under different pressure, power and proportion of reactant source gases. a-Si/SiO2 MQW(multi-quantum well) with high quality was deposited under suitable conditions, in which the thickness of the a-Si layers is several nanometers. The sample of a-Si/SiO2 MQW was crystallized by laser annealing. Because of the confinement of the SiO2 layers, crystalline grains were formed during the a-Si layers were being crystallized. The size of the crystalline grains were not more than the thickness of the a-Si layers. The a-Si layers were crystallized to be nanometer crystalline silicon(nc-Si), therefore, nc-Si/SiO2 MQW was formed. For the a-Si/SiO2 MQW with 4.0nm a-Si wells separated by 5nm SiO2 barries, most of the a-Si were crystallized to silicon grains after laser annealing,and the size of the grains is 3.8nm. Strong photoluminescence with three peaks from the nc-Si/SiO2 MQW was detected at 10K. The wavelength of the peaks were 810nm, 825nm and 845nm, respectively.

The diphasic nc-Si/a-Si : H thin film with improved medium-range order

A series of silicon film samples were prepared by plasma enhanced chemical vapor deposition (PECVD) near the threshold from amorphous to nanocrystalline state by adjusting the plasma parameters and properly increasing the reactions between the hydrogen plasma and the growing surface. The microstucture of the films was studied by micro-Raman and Fourier transform infrared (FTIR) spectroscopy. The influences of the hydrogen dilution ratio of silane (R-H = [H-2]/[SiH4]) and the substrate temperature (T-s) on the microstructural and photoelectronic properties of silicon films were investigated in detail. With the increase of RH from 10 to 100, a notable improvement in the medium-range order (MRO) of the films was observed, and then the phase transition from amorphous to nanocrystalline phase occurred, which lead to the formation of diatomic hydrogen complex, H-2* and their congeries. With the increase of T-s from 150 to 275 degreesC, both the short-range order and the medium range order of the silicon films are obviously improved. The photoconductivity spectra and the light induced changes of the films show that the diphasic nc-Si/a-Si:H films with fine medium-range order present a broader light spectral response range in the longer wavelength and a lower degradation upon illumination than conventional a-Si:H films. (C) 2004 Elsevier B.V. All rights reserved.

Study on optical band gap of boron-doped nc-Si : H film

The optical band gap (E-g) of the boron (B)-doped hydrogenated nano-crystalline silicon (nc-Si:H) films fabricated using plasma enhanced chemical vapor deposition (PECVD) was investigated in this work. The transmittance of the films were measured by spectrophotometric and the E-g was evaluated utilizing three different relations for comparison, namely: alphahnu=C(hnu-E-g)(3), alphahnu=B-0(hnu-E-g)(2), alphahnu=C-0(hnu-E-g)(2). Result showed that E-g decreases with the increasing of Boron doping ratio, hydrogen concentration, and substrate's temperature (T-s), respectively. E-g raises up with rf power density (P-d) from 0.45W.cm(-2) to 0.60w.cm(-2) and then drops to the end. These can be explained for E-g decreases with disorder in the films.