[10a-N305-1~10] CS.8 Code-sharing Session of 4.5 & 17

▲ [10a-N305-4] Dominating Interlayer Resonant Energy Transfer in Type-II Atomically Thin Semiconductor Heterostructures

〇(PC)Arka Karmakar¹, Abdullah Al-Mahboob¹, Christopher E. Petoukhoff¹, Oksana Kravchyna¹, Nicholas S. Chan¹, Takashi Taniguchi², Kenji Watanabe², Keshav M. Dani¹ (1.OIST, 2.NIMS)

Keywords:Energy transfer, Heterostructures, Transition metal dichalcogenide

Newly emerging transition metal dichalcogenide (TMD) materials have gained significant interest in last decade due to their unique quantum properties in monolayer regime. Type-II heterostructures (HSs) are building blocks of next generation electronic and optoelectronic devices. Earlier studies have found that in type-II TMD HSs, the dominating carrier relaxation pathway is the interlayer charge transfer (CT) mechanism. Here, this report shows in a type-II HS formed between monolayers of group-6 and group-7 TMD materials, nonradiative energy transfer (ET) from higher to lower work function material dominates over the traditional CT process even without a charge-blocking interlayer. In this study, group-6 TMD was used as acceptor material and group-7 as donor material. Without charge-blocking interlayer, we measure a 70% ET efficiency, leading to 3.6 times photoluminescence (PL) enhancement from the acceptor material in HS area. By completely blocking the interlayer CT process with few layers of hexagonal boron nitride (hBN) we achieved more than one order magnitude higher PL emission from the acceptor material in the HS area. PL enhancement factor (I/I_o) which is proportional to the ET, shows a distance (d) dependency of 1/d², revealing the interaction between the donor-acceptor material via 2D-to-2D dipole coupling. This work reveals that the nature of this ET is truly a resonant effect by showing that in a similar type-II HS formed by the same group-7 and slightly higher optical gap group-6 material, the CT dominates over ET, resulting in a severely quenched acceptor PL. This study not only provides significant insight into the competing interlayer processes, but also shows an innovative way to increase the PL quantum yield of the desired TMD material using ET process by carefully choosing the right material combination.