Time-resolved PL Spectra Study of Ordered Ga_(0.52)In_(0.48)P Alloys

【中文摘要】 在室温和低温液氮下 ,研究了有序和无序 Ga0 .52 In0 .4 8P的时间分辨发光谱。对实验结果的拟合表明 ,有序 Ga0 .52 In0 .4 8P的发光呈双指数规律衰退。其中快过程对应着有序区域上载流子的复合 ,慢过程则对应着有序区域和无序区域的空间分离中心上载流子的复合。无序 Ga0 .52 In0 .4 8P的发光在室温下呈单指数规律衰退。同时从低温下的时间分辨发光谱还可以看出有序样品的发光峰随着延迟时间的变长而蓝移 ,说明低温下在有序 Ga0 .52In0 .4 8P中存在着载流子从无序区域到有序区域的转移 【英文摘要】 The time resolved photoluminescence(TRPL) spectra of ordered and disordered Ga 0.52 In 0.48 P alloys grown by MOVPE were investigated.The least square fitting of the luminescence decay spectra of ordered alloys shows that there exist two exponential processes:The short lifetime process was corresponding to the high energy peak in PL spectra which is attributed to the recombination of the carriers in the ordered domains and the long lifetime process was corresponding to the low energy peak in the P...国家自然科学基金 (编号:69776011); 福建省自然科学基金 (编号:A9910004和 A0110007

Well Width Dependence of Band Gap Renormalization of Single ZnO/MgZnO Quantum Well

通过室温下的时间积分光致发光(Pl)谱,研究了阱宽lW渐变的znO/Mg0.1zn0.9O单量子阱在高激发强度下的能带重正化与阱宽的关系。实验中光生载流子浓度为n=1.6x1014CM-2,在lW从2.3 nM渐变到4.3 nM,Pl谱峰位的红移量从5.9 MEV变化到97.1 MEV。红移量随阱宽增大而增加,但增加率却逐渐减少。当lW>2αb(αb,znO体材料激子玻尔半径,约为2 nM)时,红移量逐渐呈现出饱和的趋势(100 MEV)。研究发现峰位的红移是由于多体效应所导致的能隙收缩以及在高的激发强度下带内填充效应的这两种机理相互竞争的结果。Band gap renormalization of ZnO/Mg0.1Zn0.9O single quantum well(QW) with gradual well width(Lw) is studied by room-temperature time integrated photoluminescence(PL) spectra at high excitation power density.The photo-generated carrier density is n=1.6×1014 cm-2 and the magnitude of red shift of PL spectrum peak increases from 5.9 meV to 97.1 meV with Lw changing from 2.3 nm to 4.3 nm.With Lw increaseing,the red shift increases but the increase rate gradually decreases.When Lw>2αB(αB,the exciton Bohr radius of ZnO bulk,is about 2 nm),the red shift starts to be gradually saturated.It is found that the red shift is the competition result of energy gap contraction due to many body effect and intraband filling effect at high excitation power density.The result is useful for designing and application of ZnO QW-based optoelectronic devices.国家973计划(2004CB719804);国家自然科学基金(60876007);广州市科技局推荐项目(2005Z3-C7451)资助课

Damage to mangroves from extreme cold in early 2008 in southern China

通讯作者Author for correspondence (E-mail: [email protected])2008年初,我国南方19个省经历了50年一遇的持续低温雨雪冰冻天气。极端气候对华南沿海各省的红树林区造成不同程度的危害。2008年3月,在我国南方各省红树林区的10个代表性地点,对这次寒害造成的红树植物伤害程度进行了系统的调查。结果表明:冬季低温对红树林的影响极为显著,特别是在低纬度的海南、广西和广东湛江,由于极端低温正值夜间退潮,对红树林的影响更为显著;在纬度较高的福建,本地红树种类秋茄(Kandelia obovata)、桐花树(Aegiceras corniculatum)和白骨壤(Avicennia marina)及引种的木榄(Bruguiera gymnorrhiza)等,由于长期适应于冬季较低的气温或在种植前经过抗寒锻炼,具有较强的抗寒能力。各地主要红树植物中,广布种秋茄、桐花树和白骨壤最为耐寒,其耐寒性均大于红树科的木榄、海莲(Bruguiera sexangula)和红海榄(Rhizophora stylosa)。海桑(Sonneratia caseolaris)对温度的敏感性最强,抗寒能力最低,因此,即使在其原产地海南也受到较为严重的寒害,在纬度更高的引种地出现大面积受害甚至全部死亡,而从孟加拉国引种的无瓣海桑(Sonneratia apetala)却显示出一定的抗寒能力。同一地点的红树植物幼苗的抗寒能力低于大树。此次寒害也造成了苗圃场的种苗大量死亡,成熟的植株提前落花落果,这势必会影响后继一两年内红树林的自然更新和人工造林。因此,在未来红树林造林或人工引种中,一定要考虑到红树植物的抗寒能力。国家自然科学基金(30671646和30700092);厦门大学“闽江学者”启动基

Luminescence Decay of Partially Ordered (Al_xGa_(1-x))_(0.51)In_(0.49)P(x=0.29) Alloy

【中文摘要】 利用时间分辨光谱研究了 (AlxGa1-x) 0 51In0 4 9P合金的时间衰退过程 ,观察到载流子的转移过程和PL谱峰蓝移现象。这和变温发光谱中谱峰的Z 型依赖关系相吻合。这种现象明显表明了载流子的转移过程和子带的存在 ,证实了我们对超晶格带折叠效应的猜测。子带是由于有序结构的超晶格效应使导带的L带折叠到Γ带 ,载流子在时间衰退过程中从Γ带转移到L带。时间分辨光谱的蓝移现象同时也揭示了PL变温谱中谱峰反常蓝移现象的来源 【英文摘要】 In this paper, time-resolved photoluminescence(TRPL) was applied to study the optical properties of partially ordered quaternary (Al xGa 1-x) 0.51In 0.49P(x=0.29) alloy grown by MOVPE, the process of the transfer of carriers and the blue-shift of PL peak in (Al xGa 1-x) 0.51In 0.49P(x=0.29) alloy are directly observed.Both excitation-wavelength dependence of lifetime and excitation-intensity dependence of lifetime show wide distribution of carriers along bands.In TRPL spectra measured ...福建省自然科学基资助项目 (A0110007;A9910004

Time-resolved photoluminescence spectra study of ordered Ga_(0.52)In_(0.48)P alloys

【中文摘要】 在室温和低温下 ,测试了有序Ga0 .52 In0 .4 8P的时间分辨光致发光谱 .对实验结果的分析表明 ,有序GaInP的发光呈双指数规律衰退 .室温下 ,快过程的时间常数在 12 8～ 2 5 0ps范围 ,低温 77K下则都有所变慢 ,大约在 186～ 5 64ps范围内 ;慢过程的时间常数根据不同样品有很大差异 ,室温下大约在 3 0 8～ 183 2ps之间变化 ,低温 77K下 ,则在纳秒量级 ,最长的甚至达到 2 8ns以上 .对两个过程的时间常数随激发功率密度变化的研究表明 ,快过程对应于有序区域中载流子的复合 ,慢过程则对应于有序区域和无序区域的空间分离中心上的载流子的复合 .低温下的时间分辨谱表明 ,发光峰随着延迟时间的变长而蓝移 【英文摘要】 The time resolved photoluminescence (TRPL) spectra of ordered Ga 0.5 In 0.5 P alloys grown by metalorganic vapor phase epitaxy were investigated. The least\|square fitting of the luminescence decay spectra shows that there exist two exponential processes: for the quick process the lifetime τ 1 is about 128 ps—250 ps and 186 ps—546 ps at room temperature and 77 K, respectively; and for the slow process the lifetime τ 2 is, about 308 ps—1832 ps, at room temperature and at 77 K, as long as n...国家自然科学基金 (项目编号 :69776011);福建省自然科学基金资助的

Luminescence Decay on the Nominally Disordered GaInP Alloy

【中文摘要】 报道了名义上无序GaxIn1 xP(x =0 .5 2 )合金的发光瞬态过程 ,对样品在 77K和 30 0K下不同激发强度的时间衰退过程和时间分辨光谱的分析表明 ,这块名义上无序的合金也存在很微弱的有序度 .在 77K的高激发强度下 ,衰退过程符合单指数衰退规律 ,在低激发强度下 ,符合双指数衰退规律 ;而在 30 0K下 ,衰退过程都符合双指数衰退规律 .在 77K下的时间分辨光谱里观察到了PL谱峰的蓝移现象和载流子的转移过程 【英文摘要】 Luminescence decay and Time-Resolved Photoluminescence(TRPL) spectroscopy were applied to study the transient luminescence process of the nominally disordered GaInP alloy in this paper. The luminescence decay of GaInP alloy is temperature and excitation-intensity dependent. At 77 K and under high excitation intensity, the luminescence decay shows single exponential decay, while under low excitation intensity of 77 K or at 300 K, the luminescence decay shows double exponential decay. The analysis indicates t...福建省自然科学基金 (A9910004,A0110007)资助项

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel