Record-High Work-Function p-Type CuBiP2 Se6 Atomic Layers for High-Photoresponse van der Waals Vertical Heterostructure Phototransistor.

Abstract

The notable lack of intrinsic p-type 2D layered semiconductors has hindered the engineering of 2D devices for complementary metal oxide semiconductors (CMOSs). Herein, a novel quaternary intrinsic p-type 2D semiconductor, CuBiP2 Se6 atomic layers, is introduced intothe2D family. The semiconductor displays a high work function of 5.26eV, a moderate hole mobility of 1.72 cm2 V-1 s-1 , and an ultrahigh on/off current exceeding 106 at room temperature. To date, 5.26eV is the highest work-function recorded in p-type 2D materials, indicating the ultrastable p-type behavior of CuBiP2 Se6 . Additionally, a multilayer graphene/CuBiP2 Se6 /multilayer graphene (MLG/CBPS/MLG)-based fully vertical van der Waals heterostructure phototransistor is designed and fabricated. This device exhibits outstanding optoelectronic performance with a responsivity (R) of 4.9 ×104 A W-1 , an external quantum efficiency (EQE) of 1.5 ×107 %, a detectivity (D) of 1.14 ×1013 Jones, and a broad working wavelength (400-1100nm), respectively. This is comparableto state-of-the-art 2D devices. Such excellent performance is attributed to the ultrashort transmit length and nondestructive/defect-free contacts. This leads to faster response speed and eliminates Fermi-levelpinningeffects. Moreover, ultrahigh responsivity and detectivity endow the device with applaudable imaging sensing capability. These results make CuBiP2 Se6 an ideal p-type candidate material for next-generation CMOSs logic devices.