Lin Chun-Han, Tu Charng-Gan, Chen Horng-Shyang, Hsieh Chieh, Chen Chih-Yen, Liao Che-Hao, Kiang Yean-Woei, Yang C C
Institute of Photonics and Optoelectronics, National Taiwan University, 1, Roosevelt Road, Section 4, Taipei, 10617 Taiwan.
Opt Express. 2013 Jul 29;21(15):17686-94. doi: 10.1364/OE.21.017686.
For enhancing the light extraction of a light-emitting diode, surface grating fabrication based on a simple method of combining photoelectrochemical (PEC) etching with phase mask interferometry has been demonstrated. To understand the optimum grating period in forming a surface grating on a vertical light-emitting diode (VLED), we construct a Llyod's interferometer within PEC electrolyte (KOH) to fabricate surface gratings of various periods on VLEDs for comparing their light extraction efficiencies. Also, to compare the effectiveness of light extraction enhancement between surface grating and rough surface, VLEDs with the rough surfaces fabricated with two different KOH wet etching methods are fabricated. The comparisons of VLED characterizations show that among those grating VLEDs, the light extraction is more effective in a VLED of a smaller grating period. Also, compared with VLEDs of rough surfaces, the grating VLEDs of short grating periods (<2 μm) have the higher light extraction efficiencies, even though the root-mean-square roughness of the rough surface is significantly larger than the grating groove depth.
为了提高发光二极管的光提取效率，已经证明了基于光电化学（PEC）蚀刻与相位掩膜干涉测量法相结合的简单方法来制造表面光栅。为了了解在垂直发光二极管（VLED）上形成表面光栅时的最佳光栅周期，我们在PEC电解质（KOH）中构建了一个劳埃德干涉仪，以在VLED上制造不同周期的表面光栅，从而比较它们的光提取效率。此外，为了比较表面光栅和粗糙表面之间光提取增强的效果，制造了采用两种不同KOH湿法蚀刻方法制造的具有粗糙表面的VLED。VLED特性的比较表明，在那些光栅VLED中，光栅周期较小的VLED的光提取效果更好。而且，与粗糙表面的VLED相比，光栅周期短（<2μm）的光栅VLED具有更高的光提取效率，尽管粗糙表面的均方根粗糙度明显大于光栅槽深度。
