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We construct the two-dimensional (2D) excitonic solar cells based on type II vdW heterojunctions of Janus III-VI chalcogenide monolayers and investigate the performance of the device using the first principle. The calculated solar energy absorbance of In2SSe/GaInSe2and In2SeTe/GaInSe2heterojunctions is the order of 105cm-1. The predicted photoelectric conversion efficiency of the In2SeTe/GaInSe2heterojunction can reach up to 24.5%, which compares favorably with other previously studied 2D heterojunctions. The excellent performance of In2SeTe/GaInSe2heterojunction originates from the fact that the built-in electric field at the interface of In2SeTe/GaInSe2promote the flow of the photogenerated electrons. The results suggest that 2D Janus Group-III chalcogenide heterojunction can be a good candidate for new optoelectronic nanodevices.
RESUMEN
When metal nanoparticles are functionalized with charged ligands, the movement of counterions and conduction electrons is coupled, which enables us to develop electronic devices, including diodes, transistors, and logic gates, but dynamically modulating the conductivity of a synaptic device within these materials has proved challenging. Here we show that an artificial synapse can be created from thin films of functionalized metal nanoparticles using an active silver electrode. The electric-field-injected Ag+ coordinates with carboxyl ligands that sets up a conduction bridge to increase the nanoparticle conductivity by reducing the electron tunneling/hopping energy barriers. The dynamic modulation of conductivity allows us to implement several important synaptic functions such as potentiation/depression, paired-pulse facilitation, learning behaviors including short-term to long-term memory transition, self-learning, and massed leaning vs spaced learning. Finally, based on the nonvolatile characteristics, the metal nanoparticle synapse is used to build a single-layer hardware spiking neural network (SNN) for pattern recognition.
Asunto(s)
Nanopartículas del Metal , Sinapsis , Cationes , Electrónica , LigandosRESUMEN
Edge contact between two-dimensional materials and metal can achieve small contact resistance because of strong interaction. In this work, we investigated the electronic transport of in-plane (IP) heterojunctions based on Ti/WSSe and Sn/WSSe using first principle calculations. The results showed that the interface bonding and metallization are found on the IP Ti/WSSe and Sn/WSSe contact interface, indicating that the Ohmic contacts are formed between Ti, Sn and WSSe. Then, we constructed double-gate model to investigate the performance of the IP Ti and Sn contacted 5.1 nm WSSe Schottky barrier field-effect transistors (SBFETs). The calculated on-state current of the IP Ti contacted 5.1 nm WSSe SBFETs is 406.3 µA/µm. While, the on-state current of the Sn contacted 5.1 nm WSSe SBFETs reachs up to 1104.2 µA/µm, which is far beyond the requirements of the requirements of International Technology Roadmap for Semiconductor (ITRS) HP application targets. Our study will provide a guide for high performance transistors based on IP metal/WSSe configurations in the future.
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The electronic transport properties of in-plane graphene/MoS2/graphene heterojunctions are studied using density functional theory and the nonequilibrium Green's function method. It is found that different covalent bond connections cause different electron distributions, such as accumulation or depletion, on the contact surface. The C-S structure exhibits more electron accumulation and depletion, indicating that the electrons can easily transfer from MoS2 to graphene. Since the three structures all form covalent or ionic bonds, the tunneling barrier for carriers is very small. The C-S structure exhibits a smaller p-type Schottky barrier, indicating that it has better transport properties than the other two structures. We found that the effective doping method can reduce the Schottky-barrier height (SBH), resulting in smaller contact resistance. Thus, the current-voltage curves of the undoped and doped C-S structures exhibit rectification and approximately linear characteristics under a given bias, which agrees with experimental reports. These results provide insight for designing high-performance devices.
RESUMEN
A metal electrode modification process for AlGaN-based metal-semiconductor-metal (MSM) photodetectors have been introduced to enhance the response of solar-blind ultraviolet (UV) light detection. The hexadecanethiol organic molecules are chemically adsorbed on the electrodes of high-Al-content Al0.6Ga0.4N MSM solar-blind UV photodetectors, which can reduce the work function of the metal electrode and change the height of the Schottky barrier. This modification process significantly increases the photocurrent and responsivity of the device compared with the referential photodetector without modification. Additionally, the adverse effects caused by the surface state and polarization of the AlGaN materials are effectively reduced, which can be beneficial for improving the electrical performances of III-nitride-based UV photodetectors.