光增强湿法刻蚀提高Si衬底垂直结构GaN基LED的出光效率

Improvement for Extraction Efficiency of Vertical GaN-Based LED on Si Substrate by Photo-Enhanced Wet Etching

以0.1 MK2S2O8+KOH和氙灯分别作为刻蚀剂和紫外光源,采用光增强湿法刻蚀转移衬底的垂直结构GaN基LED的n型GaN,对N面有电极和没有电极的芯片的n型GaN层进行刻蚀。结果表明,在相同的刻蚀条件下,N面有电极的n型GaN层刻蚀速率明显大于没有电极的n型GaN;而它们的均方根粗糙度(RMS)则结果相反。刻蚀后的形貌呈圆锥型凸起。20 mA下刻蚀后的裸芯光输出功率较刻蚀前提高了88.5%。

The surface of n -GaN is fabricated by photo-enhanced wet etching with the etchant of 0.1 M K2 S2O8 ＋ KOH and the illumination of Xe ultraviolet light. The n-GaN with an electrode on its surface is etched. Under the same etching condition, n-GaN with an electrode on its surface shows a higher etching rate but a lower root-mean- error（RMS） compared with n-GaN without an electrode. Mter etching, the surface of n-GaN is covered by hexagonal cones. Output power of the LED is improved by 88.5 % after etching with 20 mA current.