MOCVD growth of high-reflectivity AlN/GaN distributed Bragg reflectors

利用金属有机物化学气相沉积(MOCVD)方法在蓝宝石c面衬底上制备出高反射率AlN/GaN分布布拉格反射镜(DBR)。利用分光光度计测量,在418 nm附近最大反射率达到99%。样品表面显微照片显示,有圆弧形缺陷和少量裂纹出现;在缺陷和裂纹以外的区域,DBR具有较为平坦的表面,其粗糙度在10μm×10μm面积上为3.3 nm左右。样品的截面扫描电镜(SEM)照片显示,DBR具有良好的周期性。对反射率和表面分析的结果表明,该样品达到了制备GaN基垂直腔面发射激光器(VCSEL)的要求。A high reflectivity AlN/GaN distributed Bragg reflector(DBR) is grown on c-plane sapphire substrate by metalorganic chemical vapor deposition(MOCVD).A peak reflectivity of 99% is observed around 418 nm by spectrophotometer.Compass-shape defects and a few cracks are observed on the surface.The surface root mean square(RMS) of roughness in the flat area is around 3.3 nm over a 10 μm×10 μm area.The cross-sectional scanning electron microscope(SEM) image reveals the good periodicity of DBR.Considering the peak reflectivity and surface morphology,the DBR can be used to fabricate GaN-based vertical cavity surface emitting laser(VCSEL).国家高技术研究“863”计划资助项目(2006AA03Z409

2001年亞洲盃女子足球比賽得失分特徵之研究

[[abstract]]Abstract This study analyses the goals scored in the ten crucial matches at the 2001 Women’s Asian Soccer Tournament, correlating the results obtained to period of playing time, shooting position, player position, and method of scoring. The results obtained were put to a one-way ANOVA analysis with α=.05 level。 The results obtained were as follows: 1. No notable difference was observed for goals scored in relation to playing period. 2. No notable difference was observed for goals scored in relation to shooting position. Most goals were scored from area A (the six yard box). Least goals were scored from area C (left and right sides of the penalty area). 3. A notable difference was observed for goals scored in relation to playing position. Attackers scored more goals than defenders. 4. An analysis of scoring method returned the following results: (1) Most goals scored in open play occurred from crosses to the near and far posts and from through passes. Fewer goals occurred from crossovers, overlaps, wall passes and back passes. (2) No notable difference was observed for goals scored from set plays. (3) An analysis of the occurrence of scoring opportunities revealed that most scoring chances arose from passes by team-mates. Fewer chances occurred from defensive fouls, defensive mistakes and individual dribbles by the attacking team. (4) A notable difference was observed in method of shot. Tap-ins and strong instep shots showed a notable difference compared to other methods of shooting. 5. No notable difference was observed in an analysis of goals scored from defensive mistakes.

新化林場柚木林之植群結構分析

The main point of the research is to do a detail research by using ecological methods about the community structure and species diversity of Common Teak plantation at the second and third compartment in Hsin-Hua Forest Station, National Chung-Hsing Univer本研究以生態方法針對中興大學新化林場第二、三林班柚木林之植群結構及物種歧異度進行調查研究，期供柚木林經營管理之基本參考資料。調查顯示樣區喬木層之植物種類共計有29種，地被層植物則高達115種。矩陣群團分析中若以相似性指數45％作為臨界值，則可將所有樣區歸為同一群，可見所選15個柚木林樣區頗具代表性。物種歧異度之分析顯示；Margalef種豐多度指數（Dmg）達0.90以上，Shannon訊息統計指數（Hsw）達1.11以上，Shannon均勻度指數（Esw）達0.60以上，Simpson種豐富度指數（D

惠蓀林場小出山闊葉樹次生林植群之生產力與歧異度分析

生產力與歧異度為林業經營的重要評審，本研究以林分蓄積和種豐富度指數第二項指標，探討惠蓀林場小出山闊葉樹次生林，從過去經營施業後至今的植群動態變化概測。結果顯示:1983至1997年間經三種處理的闊葉時次生林，其每公煩材積增加40-50 m3，顯示闊葉樹次生林即使未經任何處理，然因自我調節能力亦可調整適當之立木株數，載其材積增加，且比疏伐處理的樣區具有較高之生產力。而就Shannon訊息統計指數、Berger豐富度指數、McIntosh豐家度指數、Simpson豐富度指數、Shannon均勻指數與McIntProductivity+and+diversity+are+important+criteria+of+forest+management.+The+purpose+of+the+study+is+via+the+two+indices+of+stand+growing+stock+and+species+abundance+indices+to+discuss+the+vegetation+dynamic+of+the+broadleaf+secondary+forest+at+the+Mt.+Sh

NICOTINE CHEMICAL SENSOR BASE ON MULTIWALLED CARBON NANOTUBES-ALUMINA COATED SILICA MODIFIED GLASSY CARBON ELECTRODE

本發明係關於一種偵測尼古丁的化學感測器，其中多層奈米碳管(multiwalled carbon nanotube)包含有三氧化二鋁包覆二氧化矽奈米顆粒複合物之薄膜，該薄膜修飾於玻璃碳電極(glassy carbon electrode)表面上。藉由多層壁奈米碳管優異之導電性質及高表面積，能有效提供較低的氧化電位做為偵測尼古丁的氧化反應，且具有抗電極毒化的能力。本發明亦揭示一種製造此感測器之方法

1999年第30屆國際物理奧林匹亞競賽理論競賽試題

[[issue]]226

1999年第30屆國際物理奧林匹亞競賽實驗競賽試題

[[issue]]227

Fabrication of GaN-based Vertical Cavity Surface Emitting Lasers

作者在我国大陆首次实现了GaN基垂直腔面发射激光器(VCSEL)的激射.首先采用金属有机物化学气相沉积(MOCVD)技术在蓝宝石衬底上进行高质量氮化物增益区的外延生长,然后在表面沉积高反射介质膜分布布拉格反射镜(DBR).将样品键合到其它支撑片上后,采用激光剥离技术将蓝宝石衬底去除.再在去除蓝宝石后露出的氮化物表面沉积第二组介质膜DBR制成VCSEL.在室温光泵条件下,观察到VCSEL的激射,激射波长449.5 nm,阈值6.5 mJ/cm2,激射峰的半高宽小于0.1 nm,这些指标达到了国际领先水平.本文为进一步研制实用化氮化物VCSEL奠定了重要的基础.GaN-based vertical surface emitting lasers(VCSELs) have potential applications in various fields such as high-density optical storage.This paper is the first report in mainland of China on lasing action of GaN-based VCSEL.High-quality nitride active gain region was grown on an Al2O3 sapphire substrate using metalorganic chemical vapor deposition(MOCVD).Then a high-reflectivity dielectric distributed Bragg reflector(DBR) was deposited on the surface.After bonding a supporting plate on the surface,the sapphire substrate was removed by a laser-lift-off method and the second dielectric DBR was deposited on the exposed GaN surface to form a VCSEL structure.Lasing action was confirmed under optical pumping at room temperature.The lasing wavelength,threshold and linewidth were 449.5 nm,6.5 mJ/cm2 and 0.1 nm,respectively.The threshold and linewidth are better than those ever reported.The result of this work laid important foundation of current-injected VCSEL based on nitride semiconductors.科技部国家高科技研究发展计划(863计划)资