Hot carrier-enhanced interlayer electron –hole pair multiplication in 2D semiconductor heterostructure photocells

Nature Nanotechnology 12, 1134 (2017). doi:10.1038/nnano.2017.203 Authors: Fatemeh Barati, Max Grossnickle, Shanshan Su, Roger K. Lake, Vivek Aji & Nathaniel M. Gabor Strong electronic interactions can result in novel particle–antiparticle (electron–hole, e–h) pair generation effects, which may be exploited to enhance the photoresponse of nanoscale optoelectronic devices. Highly efficient e–h pair multiplication has been demonstrated in several important nanoscale systems, including nanocrystal quantum dots, carbon nanotubes and graphene. The small Fermi velocity and nonlocal nature of the effective dielectric screening in ultrathin layers of transition-metal dichalcogenides (TMDs) indicates that e–h interactions are very strong, so high-efficiency generation of e–h pairs from hot electrons is expected. However, such e–h pair multiplication has not been observed in 2D TMD devices. Here, we report the highly efficient multiplication of interlayer e–h pairs in 2D semiconductor heterostructure photocells. Electronic transport measurements of the interlayer I–VSD characteristics indicate that layer-indirect e–h pairs are generated by hot-electron impact excitation at temperatures near T = 300 K. By exploiting this highly efficient interlayer e–h pair multiplication process, we demonstrate near-infrared optoelectronic devices that exhibit 350% enhancement of the optoelectronic responsivity at microwatt power levels. Our findings, which demon...
Source: Nature Nanotechnology - Category: Nanotechnology Authors: Tags: Letter Source Type: research