p-n结二极管结区边界附近的交流电特性

基于p-n结二极管的理想工作状态的基本假定，推导了二极管在交流电下工作时其基区和p-n结分界面附近上的时间常数与二极管空间尺寸、扩散长度、载流子寿命和外加交流电频率等的依赖关系.结果发现高频和低频两种状态下二极管各类特征参量对时间常数的作用不一样.低频条件下，二极管的时间常数由材料本身来决定，与外加电流频率无关.高频情况下，时间常数则与半导体材料性质无关，只由外加交流电的频率来决定.     

Clerodendrumol,A New Triterpenoid from Clerodendrum yaundense Gürke (Lamiaceae)

A new lupane‐type triterpene named clerodendrumol ( 1 ), i.e., (16α)‐lupa‐12,20(29)‐dien‐16‐ol, together with five known compounds, octacosa‐(5Z,9Z)‐dienoic acid ( 3 ), tetracosanoic acid ( 4 ), genkwanin ( 5 ), (12S)‐hydroxyoctadeca‐(9Z,13E,15E)‐trienoic acid ( 6 ), and (9S)‐hydroxyoctadeca‐(10E,12E)‐dienoic acid ( 7 ), were isolated from the twigs of Clerodendrum yaundense. O‐Acetylclerodendrumol ( 2 ), a derivative of 1 , was prepared by a standard acetylation procedure applied to compound 1 . The structure of the new compound was elucidated using spectroscopic analysis (NMR and MS) data, and chemical conversions (acetylation and deacetylation). The human breast cancer cell line (MDA‐MB‐231) was sensitive to all test samples, and clerodendrumol ( 1 ) as well as its derivative 2 had good activity (IC₅₀ values 7.5 and 13.2 μM ). Genkwanin ( 5 ) exhibited strong activity on HeLa cell line with IC₅₀ 7.8 μM .     

p-n结二极管结区边界附近的交流电特性

基于p-n结二极管的理想工作状态的基本假定,推导了二极管在交流电下工作时其基区和p-n结分界面附近上的时间常数与二极管空间尺寸、扩散长度、载流子寿命和外加交流电频率等的依赖关系.结果发现高频和低频两种状态下二极管各类特征参量对时间常数的作用不一样.低频条件下,二极管的时间常数由材料本身来决定,与外加电流频率无关.高频情况下,时间常数则与半导体材料性质无关,只由外加交流电的频率来决定. 关键词： p-n结二极管 时间常数 载流子 分界面