三端1.3μm InGaAsP／InP双区共胺激光器

研制成功了弱调Ｑ及强调Ｑ两种三端１．３μｍ ＩｎＧａ ＡｓＰ／ＩｎＰ双区共腔激光器，其Ｐ／Ｉ特性分别呈二极管激射特性和吸收型双稳特性，两种激光器均实现了室温连续（直流）工作，吸收区电极的设置使两种器件的Ｐ／Ｉ特性均获得了大范围调节。     

1.52um InGaAsP／InP分别限制量子阱激光器

报导了在６００℃生长温度下以三甲基镓（ＴＭＧａ）和三甲基铟（ＴＭＩｎ）为Ⅲ族源，用低压金属有机气相沉积（ＬＰ－ＭＯＣＶＤ）技术生长出的高质量１．６０ｕｍ和１．３ｕｍ ＩｎＧａＡｓＰ材料，以及在其分别限制量子阱结构生长的情况下，用质子轰击方法制得的条形结构量子阱激光器。该激光器在室温下直流阈值电流为１００ｍＡ。     

1.3μmInGaAsP／InP增益耦合型分布反馈激光器

采用两次液相外延技术制备了１．３μｍＩｎＧａＡｓＰ／ＩｎＰ内含吸收光栅的增益耦合型分布反馈激光器，成功地利用湿法腐蚀光栅技术，控制吸收光栅的形状和占空比，实现了增益耦合型ＤＦＢ激光器在室温下的脉冲激射，器件表现出了ＤＦＢ模式的单模工作特性。     

LP-MOCVD生长大功率InGaAsP/GaAs量子阱激光器

设计并利用LP－MOCVD生长了InGaAsP/GaAs分别限制单量子阱结构,采用无铝的InGaP做光学包层。腔面未镀膜情况下,测试10支条宽100μm,腔长1mm的激光器样品,连续输出功率超过1W,阈值电流密度为330～490A/cm2,外微分量子效率为55％～78％,中心发射波长为(808±3)nm。     

1.3μmInAsP/InGaAsP应变补偿量子阱激光器

采用气态源分隔束外延方法及应变补偿生长工艺生长了ＩｎＡｓＰ／ＩｎＧａＡｓＰ应变补偿多量子阱激光器材料,采用选择刻蚀和聚酰亚胺隔离工艺制成了脊波导型１．３μｍ激光器芯片并对芯片性能进行了统计测量,测量结果表明此种激光器芯片在室温下的阈值电流可小于１０ｍＡ,在２５℃至９０℃温度范围内特征温度大于９０Ｋ,并表现出较好的单纵模特性。     

1.48μm大功率GaInAsP／InP激光器

用两步液相外延法研制出１．４８μｍ大功率ＧａＩｎＡｓＰ／ＩｎＰ激光器，尾纤输出功率大于３０ｍＷ。用作掺铒光纤放大器的泵浦光源，双向泵浦小信号增益２８ｄＢ，经较长时间的实际运行，表明器件性能稳定可靠，温度特性好。     

1．52μmInGaAsP／InP分别限制量子阱激光器

报导了在６００℃生长温度下以三甲基镓（ＴＭＧａ）和三甲基铟（ＴＭＩｎ）为Ⅲ族源，用低压金属有机气相沉积（ＬＰ－ＭＯＣＶＤ）技术生长出的高质量１．６０μｍ和１．３μｍＩｎＧａＡｓＰ材料，以及在其分别限制量子讲结构生长的情况下，用质子轰击方法制得的条形结构量子阱激光器。该激光器在室温下直流阈值电流为１００ｍＡ。     

用离子注入的方法实现InGaAs/InGaAsP激光器材料的量子阱混合

为了在光开关器件的局部区域实现量子阱混合,选用1～2MeV、1×1013～5×1013cm－2的P＋离子注入到InGaAs/InGaAsP分别限制多量子阱（SCH－MQW）激光器结构,在700oC下快速热退火90s。发现光致发光谱的峰值位置发生蓝移9～89nm。蓝移的大小随着注入能量和剂量的增大而增大,并且能量比剂量对蓝移的影响更大。     

Influence of substrate conductivity type on the thickness and composition of epitaxial layers grown by Liquid Phase Epitaxy

It is shown that the conductivity of the substrate has a non negligible effect on the thickness and composition of epitaxial layers grown by Liquid Phase Epitaxy. The growth experiments have been done on the systems GaAs/GaAs, GaAlSb/GaSb and GaInAsSb/GaSb. To insure strictly the same growth conditions the growth was done simultaneously, from the same liquid phase, on the different substrates.     

InGaAsP/InP long wavelength quantum well infrared photodetectors

High quality InGaAsP/InP MQWs structures, grown by solid source molecular beam epitaxy, with different doping concentrations in the wells were investigated. High doping concentrations benefits absorption but is not good for dark current. The photocurrent spectra and peak values are sensitive to applied voltage. The total photocurrent comes from the electrons excited to two excited states. The decrease of the photocurrent peak value at high voltage can be explained by the reduction of photogenerated electrons. The detectivity of the InGaAsP/InP QWIP measured at a bias of − 2.5 V at 20 K is greater than , which is comparable to the GaAs/AlGaAs QWIPs.     

Inside Front Cover: An Ultraviolet Organic Thin‐Film Solid‐State Laser for Biomarker Applications (Adv. Mater. 1/2005)

Thin‐film organic solid‐state lasers operating in the ultraviolet wavelength region are fabricated using a novel spiro‐linked material as active organic layer in an optically pumped distributed feedback (DFB) structure in work reported by Riedl and co‐workers on p. 31. The laser wavelength is tunable between 377.7 nm and 395 nm, the shortest laser wavelength reported so far for thin‐film organic solid‐state lasers. The lasers' suitability for spectroscopic applications was tested by use as an excitation source for solutions containing the common fluorescent dyes Coumarin 6, Coumarin 152, and Rhodamine 6G.     

Zn0.9Mg0.1O:Ga宽带隙导电膜的 PLD制备及性能研究

利用脉冲激光沉积法(PLD)制备了Ga掺杂的Zn0.9Mg0.1O(ZMOGa)宽带隙透明导电薄膜.采用各种分析手段研究了沉积温度和真空退火处理对薄膜结构、表面形貌及光电性能的影响.结果表明,制备的薄膜具有ZnO(002)择优取向;200℃下沉积的薄膜通过3×10-3Pa的真空400℃退火2h后,其电阻率由8.12×10-4Ω·cm减小到4.74×10-4Ω·cm,禁带宽度则由原来的3.83eV增加到3.90eV.退火处理增强了薄膜的择优取向和结晶度、增加了禁带宽度、提高了载流子浓度并使其透射谱线的光学吸收边发生蓝移现象.     

Epitaxial orientation and morphology of β-FeSi2 produced on a flat and a patterned Si(001) substrates

The epitaxial growth of β-FeSi₂ films produced on flat and patterned Si(001) substrates under various substrate temperatures (T_s) with deposition rates of Fe (V_Fe) was investigated by transmission electron microscopy (TEM). In the film deposited on the flat Si(001) substrate, precipitates of flat-bottom shaped β-FeSi₂ and those of round-bottom shaped α-FeSi₂ were formed at T_s = 500 °C and V_Fe = 0.02 nm/s. The β-FeSi₂ adopted the epitaxy to (001)_Si plane, while α-FeSi₂ selected the epitaxy to {111}_Si planes inside the Si matrix. At T_s = 350 °C and V_Fe = 0.01 nm/s, a continuous β-FeSi₂ layer were formed epitaxially on the Si(001) substrate without forming α-FeSi₂. It was found that the lower temperature and the higher Fe-concentration suppress the formation of α-FeSi₂ and promote the formation of β-FeSi₂. In addition, the morphology of β-FeSi₂ changed from fine isolated precipitates (islands) to a continuous layer with increasing the deposition rate and the substrate temperature. In the film deposited on the patterned Si(001) substrate at T_s = 500 °C and V_Fe = 0.02 nm/s, on the other hand, both β- and α-FeSi₂ precipitates were formed on the top-hills and the valleys of the patterned substrate, while only α-FeSi₂ precipitates were formed on the sidewalls. These results demonstrate that not only the growth conditions but also geometric situations affect strongly the epitaxial growth of FeSi₂ precipitates.     

Laser surface alloying of medium carbon steel with SiC(P)

Laser surface alloying (LSA) is increasingly recognised as a powerful surface modification tool to enhance the wear and corrosion resistance of engineering components. The present work deals with laser alloying of medium carbon steel with silicon carbide using a high-power CO₂ laser. A processing regime, identifying an appropriate laser power-scan speed combination for achieving defect-free alloyed layers, has been established during the study. The influence of repetitive scans on the alloyed layer properties was also subsequently investigated in a comprehensive manner. Repetitive scanning was found to affect substantially the laser-alloyed zone (LAZ) and heat-affected zone dimensions, as well as the phase constitution of the laser-alloyed layers. The microstructure in the LSA layers was also observed to vary significantly with the number of scans, besides changing quite distinctly with depth in the LAZ. Tribological tests revealed considerable improvement in abrasive wear performance by laser surface alloying, and the results also emphasise the need to control the number of repetitive scans to achieve optimum performance.