Single In x Ga1-x As nanowire/p-Si heterojunction based nano-rectifier diode

Broadband Photodetector for Ultraviolet to Visible Wavelengths Based on the BA2PbI4/GaN Heterostructure

Two-dimensional (2D) organic-inorganic hybrid perovskites (OIPs) have exhibited ideal prospects for perovskite photodetectors (PDs) owing to their remarkable environmental stability, tunable band gap, and structural diversity. However, most perovskites face the great challenge of a narrow spectral response. Integrating 2D OIPs with a suitable wide band gap semiconductor gives opportunities to broaden the response spectra. Here, a photodetector based on the BA2PbI4/GaN heterostructure with a broadband photoresponse covering from the ultraviolet (UV) to visible band is designed. We demonstrate that the device is capable of detecting in the UV region by p-GaN being integrated with BA2PbI4. The morphology and material optical properties of BA2PbI4 are characterized by transmission electron microscopy (TEM) and photoluminescence (PL). Additionally, the current-voltage (I-V) characteristics and photoresponses of the BA2PbI4/GaN heterojunction photodetector are investigated. The response spectrum of the photodetector is broadened from the visible to UV region, exhibiting good rectifying behavior in the dark conditions and a broadband photoresponse from the UV to the visible region. Additionally, the energy band is used to analyze the current mechanism of the BA2PbI4/GaN heterojunction PD. This study is expected to provide a new insight of optoelectronic devices by integrating 2D OIPs such as BA2PbI4 and wide-band-gap semiconductors such as GaN to broaden the response spectra.

Lateral Fully Organic P-N Diodes Created in a Single Donor-Acceptor Copolymer

P-N junctions exist in many solid-state organic devices, such as light-emitting diodes, solar cells, and thermoelectric devices. Creating P-N junctions by bulk chemical doping in a single organic material (like silicon doped by boron and phosphorus) may capitalize the vast scientific and technological groundwork established in the inorganic semiconducting field. However, high-performance single-organic-material P-N junctions are seldom reported, because the diffusion of the dopant counterions often leads to transient rectification properties. Herein, a new type of lateral fully organic diodes created in single donor-acceptor (D-A) copolymer films with only one P-type dopant is reported. The achieved lateral devices exhibit high current densities of ≈3.83 A cm^-2 and a high rectification ratio of ≈2100, which are beyond the requirements for high-frequency identification tags. The P- to N-type polarity switching mechanism is proposed after spectroscopic and structural tests. Decent stability of the organic diode is obtained, which is due to the long channel length and low diffusion speed of the large size of dopants. This work opens the opportunities to create P-N junctions in ways of silicon-based inorganic semiconductors and promises new opportunities for integrating organic materials for flexible and printable organic devices.

Rectification, transport properties of doped defective graphene nanoribbon junctions

The transport properties and rectification behavior of junctions which contain armchair graphene nanoribbons (AGNRs) with double vacancy defects or nitrogen-doped in three different sizes of 9, 10 and 12 atoms are studied. The non-equilibrium Green function method and density functional based tight-binding approach are used for different computations. The double vacancy (DV) defects are along the direction of current pathways of graphene devices. We calculated transmission probability, density of states, the current-voltage curves, rectification ratio, and electrodes band structures. We found that I-V graph has nonlinear characteristic and displays rectification behavior. Devices which posses the size of 9 atoms show significant sign of rectification in contrast to other cases (10, 12 atoms). But the current value is more important for the device of 12 atoms size. Moreover, it is shown that extra energy bands are created by the DV defects and nitrogen (N) doped atoms. These bands of DV defects and N-doped cause the Fermi level to shift upwards and can change the behavior (n-type semiconductor, or metal-like) of devices of 9, 10 and 12 AGNRs. Also, various orbital distributions of MPSH (molecularly projected self-consistent Hamiltonian) states in the DV-9AGNR device are investigated.