采用脉冲和直流两种驱动模式分别驱动同一批次的白光LED灯珠,对比分析了在“视觉亮度”一致时两种情况下的光色电性能,并研究了人眼视觉惰性对白光LED性能的影响。研究发现,在低脉冲占空比下,脉冲驱动LED的电流和发光效率比直流驱动的低,并且随着占空比的增加,两者的差值逐渐减小并趋于相等;当脉冲占空比高于70%时,两者驱动电流的差值增加,而脉冲驱动的发光效率却高于直流驱动的发光效率。此外,相比直流驱动,高脉冲电流驱动下的LED的发光更接近等能白光,进而增强了人眼对LED发光亮度的刺激响应,有效地提高了人眼的“视觉亮度”。

We demonstrate that ultra-thin porous alumina membrane (PAM) is suitable for controlling of both size and site of Ge nanodots on Si substrates. Ge nanodots are grown on Si substrates with PAM as a template at different temperatures with molecular beam epitaxy (MBE) method. Ordered Ge nanodot arrays with uniform size and high density are obtained at 400 and 500 oC. Spatial frequency spectrums transformed from scanning electron microscopy images through fast Fourier transform are utilized to analyze surface morphologies of Ge nanodots. The long-range well-ordered Ge nanodot arrays form a duplication of PAM at 400 oC while the hexagonal packed Ge nanodot arrays are complementary with PAM at 500 oC.