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首页> 外文会议>Light-emitting diodes: Materials, devices, and applications for solid state lighting XIII >Reduced non-thermal roll-over in violet-emitting GaInN wide-well LEDs grown on low-dislocation-density substrates
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Reduced non-thermal roll-over in violet-emitting GaInN wide-well LEDs grown on low-dislocation-density substrates

机译：在低位错密度基板上生长的发射紫光的GaInN宽阱LED的非热翻转减少

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Near-UV LEDs emitting at around 400 nm can be used e.g. as pump light source in tri-phosphor RGB white luminescence-conversion LEDs with high color rendering. Although non-thermal roll-over decreases towards shorter emission wavelengths in GaInN-based LEDs, this effect still limits the efficiency of 400 nm emitting LEDs at current densities above 50 A/cm~2. One way to overcome non-thermal roll-over is to combine a GalnN wide-well active region with the growth on low dislocation density (DD) substrates. Single-well LEDs with GalnN layer widths between 3 nm and 18 nm were grown (a) directly on sapphire substrates with a resulting DD of 10~9 cm~(-2), (b) on low DD GaN templates on sapphire (DD of 10~8 cm~(-2)), and (c) on freestanding GaN substrates (FS-GaN, DD of 4×10~7cm~(-2)). At low current densities (pulsed mode operation) the LEDs with a 3 nm GalnN QW active region showed the highest efficiency, irrespective of the substrate. However, the electroluminescence (EL) efficiency peaks at around 50 A/cm~2 and shows a clear non-thermal roll-over towards higher current densities. The efficiency of LEDs with well widths >3 nm grown on sapphire decreases with increasing well width over the whole range of current densities (≤300 A/cm~2). However, when grown on low DD GaN templates or FS-GaN, the efficiency of the LEDs with 11 and 18 nm wide GalnN layers surpasses that of the conventional LEDs (well widths ≤6 nm) for current densities ≥250 A/cm~2, yielding the highest EL efficiency of all LED-structures.
机译：例如，可以使用发射约400nm的近紫外LED。作为具有高显色性的三基色RGB白色发光转换LED中的泵浦光源。尽管在基于GaInN的LED中，非热翻转会朝较短的发射波长减小，但这种影响仍然限制了电流密度高于50 A / cm〜2时发射400 nm LED的效率。克服非热翻转的一种方法是将GalnN宽阱有源区与低位错密度（DD）衬底上的生长相结合。 GalnN层宽度在3 nm至18 nm之间的单阱LED（a）直接在蓝宝石衬底上生长，结果DD为10〜9 cm〜（-2），（b）在蓝宝石（DD）的低DD GaN模板上在独立的GaN衬底（FS-GaN，DD为4×10〜7cm〜（-2））上的10〜8 cm〜（-2））和（c）。在低电流密度（脉冲模式操作）下，具有3 nm GalnN QW有源区的LED效率最高，而与基板无关。但是，电致发光（EL）效率在50 A / cm〜2左右达到峰值，并且显示出明显的非热向更高电流密度的过渡。在整个电流密度范围内（≤300A / cm〜2），在蓝宝石上生长的阱宽度> 3 nm的LED的效率会随着阱宽度的增加而降低。但是，当在低DD GaN模板或FS-GaN上生长时，电流密度≥250A / cm〜2时，具有11和18 nm宽的GalnN层的LED的效率超过了常规LED（阱宽≤6 nm）的效率。 ，在所有LED结构中产生最高的EL效率。

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