研制了4种不同表面钝化类型Si衬底GaN基绿光LED,分别标记为样品A、B、C、D。样品A无钝化层,样品B为台面SiON钝化,样品C为侧面SiON钝化,样品D为台面和侧面均钝化。将4种样品进行了常温60 mA(电流密度312 A/cm2)下168 h的加速老化,并对比了老化前后的I-V和光衰等特性。结果表明:侧边的SiON钝化层可有效抑制有源区内非辐射复合缺陷的增加,从而有效降低器件老化后的漏电流和光衰。与台面上的SiON相比,侧边的SiON对钝化起到了决定性作用。
The green LED with vertical structure was fabricated by transferring the epilayers of GaN-based LED grown on Si(111) substrate to a new Si substrate.Four groups of LED with chip size of 200 μm×200 μm were fabricated,labeled as sample A,B,C and D,respectively.Sample A was uncoated.Top surface of sample B,sidewall of sample C and both top surface and sidewall of sample D were coated with SiON passivation layer under the same experimental condition.Electrical and optical properties were investigated after 168 hours accelerated aging under 60 mA DC current at room temperature.The results show that the sidewall-SiON layer could decrease the generation of non-recombination centers in the active layer.Thus it could reduce leakage currents and the luminous decay.Comparing to the top-surface SiON,the sidewall SiON played a decisive role in improving the reliability of the LED.