Abstract Transition metal dichalcogenide (TMD) semiconductor heterostructures are actively explored as a new platform for quantum optoelectronic systems. Most state of the art devices make use of insulating hexagonal boron nitride (hBN) that acts as a wide-bandgap dielectric encapsulating layer that also provides an atomically smooth and clean interface that is paramount for proper device operation. We report the observation of large, through-hBN photocurrents that are generated upon optical excitation of hBN encapsulated MoSe2 and WSe2 monolayer devices. We attribute these effects to Auger recombination in the TMDs, in combination with an asymmetric band offset between the TMD and the hBN. We present experimental investigation of these effects and compare our observations with detailed, ab-initio modeling. Our observations have important implications for the design of optoelectronic devices based on encapsulated TMD devices. In systems where precise charge-state control is desired, the out-of-plane current path presents both a challenge and an opportunity for optical doping control. Since the current directly depends on Auger recombination, it can act as a local, direct probe of both the efficiency of the Auger process as well as its dependence on the local density of states in integrated devices.

中文翻译：

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不对称光电效应：过渡金属二硫属化物中俄歇辅助的热空穴光电流

摘要 过渡金属二硫属化物 (TMD) 半导体异质结构作为量子光电系统的新平台被积极探索。大多数最先进的器件使用绝缘六方氮化硼 (hBN) 作为宽带隙电介质封装层，它还提供原子级平滑和清洁的界面，这对于正确的器件操作至关重要。我们报告了在 hBN 封装的 MoSe2 和 WSe2 单层器件的光激发时产生的大的贯穿 hBN 光电流的观察结果。我们将这些影响归因于 TMD 中的俄歇重组，以及 TMD 和 hBN 之间的不对称带偏移。我们对这些影响进行了实验研究，并将我们的观察结果与详细的 ab-initio 建模进行了比较。我们的观察对基于封装 TMD 器件的光电器件的设计具有重要意义。在需要精确电荷状态控制的系统中，平面外电流路径对光学掺杂控制既是挑战也是机遇。由于电流直接取决于俄歇复合，因此它可以作为俄歇过程效率及其对集成器件中局部状态密度的依赖的局部直接探针。