Hot carriers assisted mixed-dimensional graphene/MoS2/p-GaN light emitting diode

Abstract

The exploration of two-dimensional (2D) materials in highly performance optoelectronic device is critical for the practical applications. Traditionally, GaN related semiconductors uses complicated multiple quantum wells to increase the overlap of electron and hole waves for highly efficient light emitting diode (LED). In this work, through designing the Graphene/MoS2 heterostructure for increasing the hot electron lifetime and subsequently enhancing the process of carrier multiplication (CM), we successfully realize the highly efficient Graphene/MoS2/p-GaN LED with external quantum efficiencies (EQE) of 15.89% under 0.625 mA/mm2. Compared with the Graphene/p-GaN LED device, the addition of MoS2 leads to stronger light output and the maximum EQE increased by 61%. The energy bands alignment between MoS2 and GaN squeezes the hole at the MoS2 layer, when the numbers of holes are increased by graphene as a result of CM effect, which recombines with electron at the surface of GaN defects resulting in the strong light output at reversed bias. We believe that this work will bring a brand new insight of realizing high efficient 2D materials based LED and optoelectronic devices.