Shallow defects found in 2D semiconductors can ionize enough carriers to enable various applicationS

Technological applications of semiconductors depend critically on their defect properties, and in the past, researchers have made theoretical predictions that there are no shallow defects in 2D semiconductors due to weak dielectric screening. Qiu et al. unveil the physical origin of intrinsic p-type conductivity in black phosphorene (BP) and black arsenene (BAs) and found the intrinsic defects in the materials indicates large lattice-relaxation-induced intrinsic shallow acceptor defects.

The technological application of semiconductors depends critically on the doping capability to obtain enough free carriers. “Our findings make the study of defects in 2D semiconductors meaningful, because only shallow defects can ionize enough carriers in semiconductors,” said author Huixiong Deng.

The researchers investigated the properties of intrinsic defects in BP and BAs using the “transfer to real state” model. According to the symmetry analysis, the shallow acceptors arise from the formation of a pyramid- like structure near the vacancy sites, which significantly reduces the system energies after lattice relaxation. To validate their simulation, they calculated the hole concentrations that are well consistent with the experimentally measured p-type conductivity in both materials.

“Our fundamental understanding of the intrinsic defect properties for black phosphorene and black arsenene pushes researchers forward to study the properties of various impurities in both materials, applications and development in practice,” said Deng.

Consequently, 2D materials, such as black phosphorene and black arsenene, are considered to be promising alternatives in novel nanoelectronic and optoelectronic devices.

Source: “Large lattice-relaxation-induced intrinsic shallow p-type characteristics in monolayer black phosphorus and black arsenic,” by Chen Qiu, Ru-Yue Cao, Fei Wang, and Hui-Xiong Deng, Applied Physics Letters (2021). The article can be accessed at https://doi.org/10.1063/5.0038874 .