Owing to high surface-to-volume ratio, InGaN-based micro-light-emitting diodes (μLEDs) strongly suffer from surface recombination that is induced by sidewall defects. Moreover, as the chip size decreases, the current spreading will be correspondingly enhanced, which therefore further limits the carrier injection and the external quantum efficiency (EQE). In this work, we suggest reducing the nonradiative recombination rate at sidewall defects by managing the current spreading effect. For that purpose, we properly reduce the vertical resistivity by decreasing the quantum barrier thickness so that the current is less horizontally spreaded to sidewall defects. As a result, much fewer carriers are consumed in the way of surface nonradiative recombination. Our calculated results demonstrate that the suppressed surface nonradiative recombination can better favor the hole injection efficiency. We also fabricate the μLEDs that are grown on Si substrates, and the measured results are consistent with the numerical calculations, such that the EQE for the proposed μLEDs with properly thin quantum barriers can be enhanced, thanks to the less current spreading effect and the decreased surface nonradiative recombination.

由于具有较高的表面体积比，InGaN 基微型发光二极管 (μLED) 很容易受到侧壁缺陷引起的表面复合的影响。而且，随着芯片尺寸的减小，电流扩散也会相应增强，从而进一步限制载流子注入和外量子效率（EQE）。在这项工作中，我们建议通过管理电流扩散效应来降低侧壁缺陷处的非辐射复合率。为此，我们通过减小量子势垒厚度来适当降低垂直电阻率，从而减少电流水平传播到侧壁缺陷的情况。因此，表面非辐射复合方式消耗的载流子要少得多。我们的计算结果表明，抑制表面非辐射复合可以更好地提高空穴注入效率。我们还制造了在硅衬底上生长的μLED，测量结果与数值计算一致，因此，由于电流扩散效应较小，并且量子势垒降低，因此所提出的具有适当薄量子势垒的μLED的EQE可以得到增强。表面非辐射复合。