Thermoluminescence in sea sediments during the cosmogenic isotopes enhancement 35000 y BP

Summary We have measured the thermoluminescence (TL) profile of the Mediterranean Sea core CT85.5 at the same depths where the cosmogenic-isotope¹⁰Be production peak at 35 ky BP was found. Strong TL peaks are evident at 37.5 ky and 35.6 ky BP. The Fourier analysis of the TL time series running from 32.5 ky to 42.6 ky at 100 y sampling interval shows 2500 y and 500 y periodicities. We suggest that the Sun was ?active? at the time of the¹⁰Be enhancement. Paper presented at the 6th Cosmic Physics National Conference, Palermo, 3–7 November 1992.     

N2流量对GaN的形貌及光学和电学性能的影响

采用化学气相沉积法(CVD)在Si(100)衬底上以Ni为催化剂, 金属Ga和NH₃为原料合成了GaN微纳米结构, 并研究了N₂流量对产物GaN的形貌及光学和电学性能的影响。利用场发射扫描电子显微镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)、X-ray能谱仪(EDS)、光致发光谱(PL)和霍尔效应测试仪(HMS-3000)等测试手段对样品的形貌、结构、成分、光学和电学性能进行了分析。结果表明, 随着N₂流量的增加, 产物GaN的形貌发生了由微米棒到蠕虫状线再到光滑纳米线的转变;生成的GaN均为六方纤锌矿结构;样品均表现出383 nm的近带边紫外发射峰和470 nm左右的蓝光发射峰;所有样品均为n型;并对产物GaN的形貌转变机理进行了分析。