Green laser diodes (LDs) still perform worst among the visible and near-infrared spectrum range, which is called the “green gap.” Poor performance of green LDs is mainly related to the p-type AlGaN cladding layer, which on one hand imposes large thermal budget on InGaN quantum wells (QWs) during epitaxial growth, and on the other hand has poor electrical property especially when low growth temperature has to be used. We demonstrate in this work that a hybrid LD structure with an indium tin oxide (ITO) p-cladding layer can achieve threshold current density as low as 1.6 kA/cm2, which is only one third of that of the conventional LD structure. The improvement is attributed to two benefits that are enabled by the ITO cladding layer. One is the reduced thermal budget imposed on QWs by reducing p-AlGaN layer thickness, and the other is the increasing hole concentration since a low Al content p-AlGaN cladding layer can be used in hybrid LD structures. Moreover, the slope efficiency is increased by 25% and the operation voltage is reduced by 0.6 V for hybrid green LDs. As a result, a 400 mW high-power green LD has been obtained. These results indicate that a hybrid LD structure can pave the way toward high-performance green LDs.

中文翻译：

---

具有 ITO 包覆层的高功率混合 GaN 基绿色激光二极管

绿色激光二极管 (LD) 在可见光和近红外光谱范围内的表现仍然最差，这被称为“绿色间隙”。绿色LDs性能差主要与p型AlGaN包覆层有关，一方面在外延生长过程中对InGaN量子阱（QWs）施加了较大的热预算，另一方面电性能较差，尤其是在低生长温度时必须使用。我们在这项工作中证明了具有氧化铟锡 (ITO) p 包覆层的混合 LD 结构可以实现低至 1.6 kA/cm2 的阈值电流密度，这仅为传统 LD 结构的三分之一。这种改进归因于 ITO 包覆层带来的两个好处。一是通过减少 p-AlGaN 层厚度来减少 QW 上的热预算，另一个是空穴浓度的增加，因为低铝含量的 p-AlGaN 包覆层可用于混合 LD 结构。此外，混合绿色 LD 的斜率效率提高了 25%，工作电压降低了 0.6 V。结果，获得了400 mW的大功率绿色LD。这些结果表明，混合 LD 结构可以为高性能绿色 LD 铺平道路。