Методики исследования электрического контактного сопротивления в структуре металлическая пленка--полупроводник

The electrical contact resistance significantly affects the efficiency of thermoelements. In the case of high doped thermoelectric materials, the tunneling mechanism of conductivity prevails at metal-semiconductor interface, which makes it possible to obtain a contact resistance of less than 10-8 Ohm•m2. Low resistance values significantly complicate its experimental determination. Work present three techniques and a measuring stand for the investigation of contact resistance. The techniques are based on the measurement of the total electrical resistance, which consists of transient contact resistance and the resistance of the thermoelectric material with its subsequent exclusion. The developed techniques differ in the arrangement of the investigated contacts on the samples, in the methods of measurement and processing of the obtained results, and make it possible to determine the specific contact resistance of the order of 10-10 Ohm•m2.

Improving the charge injection in bottom contact organic transistor by carbon electrodes

The electrode/organic semiconductor interface in OFETs is critical to device performance. Traditional metal electrodes often produce unfavorable interfacial dipole when they are in contact with organic semiconductors, inducing a larger...

Influence of the Metal–Semiconductor Interface Model on Power Conservation Principle in a Simulation of Bipolar Devices

The purpose of the study is to present a proper approach that ensures the energy conservation principle during electrothermal simulations of bipolar devices. The simulations are done using Sentaurus TCAD software from Synopsys. We focus on the drift-diffusion model that is still widely used for power device simulations. We show that without a properly designed contact(metal)–semiconductor interface, the energy conservation is not obeyed when bipolar devices are considered. This should not be accepted for power semiconductor structures, where thermal design issues are the most important. The correct model of the interface is achieved by proper doping and mesh of the contact-semiconductor region or by applying a dedicated model. The discussion is illustrated by simulation results obtained for the GaN p–n structure; additionally, Si and SiC structures are also presented. The results are also supported by a theoretical analysis of interface physics.

Investigate and Calculation Electron Transfer Rate Constant in the N749 Sensitized Dye Contact to ZnSe Semiconductor

The dye–semiconductor interface between N749 sensitized and zinc semiconductor (ZnSe) has been investigated and studied according to quantum transition theory with focusing on the electron transfer processes from the N749 sensitized (donor) to the ZnSe semiconductor (acceptor). The electron transfer rate constant and the orientation energy were studied and evaluated depended on the polarity of solvents according to refractive index and dielectric constant coefficient of solvents and ZnSe semiconductor. Attention focusing on the influence of orientation energies on the behavior of electron transfer rate constant. Differentdata of rate constant was discussion with orientation energy and effective driving energy for N749-ZnSe system. Furthermore, the electron transfer rate constant is increased with less orientation energy at less effective driving energy while the electron transfer rate constant increased with large orientation energy with large effective driving energy, as seen as the electron transfer rate reach to 1.3109 × 1011 with less orientation energy has 0.188708eV at effective driving energy E=0.22eV comparing the rate reach to 9.7207× 10−96 with driving energy E=1.89eV and same orientation energy. In general, the electron transfer rate constant increases with increases the coupling coefficient of system, its indicate that alignment of energy levels are very good between N749 sensitized metal and ZnSe semiconductor.

Faradaic junction and isoenergetic charge transfer mechanism on semiconductor/semiconductor interfaces

Energy band alignment theory has been widely used to understand interface charge transfer in semiconductor/semiconductor heterojunctions for solar conversion or storage, such as quantum-dot sensitized solar cells, perovskite solar cells and photo(electro)catalysis. However, abnormally high open-circuit voltage and charge separation efficiency in these applications cannot be explained by the classic theory. Here, we demonstrate a Faradaic junction theory with isoenergetic charge transfer at semiconductor/semiconductor interface. Such Faradaic junction involves coupled electron and ion transfer, which is substantively different from the classic band alignment theory only involving electron transfer. The Faradaic junction theory can be used to explain these abnormal results in previous studies. Moreover, the characteristic of zero energy loss of charge transfer in a Faradaic junction also can provide a possibility to design a solar conversion device with a large open-circuit voltage beyond the Shockley-Queisser limit by the band alignment theory.

Thermal Transport Across Al-(AlxGa1-x)2O3 and Al-Ga2O3 Interfaces

(AlxGa1−x)2O3 and Ga2O3 are promising wide bandgap semiconductors for application in power electronics and radio frequency devices because of their exceptional electrical transport properties. However, the heat dissipation in these devices will be limited by the ultra-low thermal conductivity of (AlxGa1−x)2O3 and Ga2O3. Previous studies showed that these devices could achieve high power density with double-sided or top-side cooling strategies. Therefore, the thermal transport across metal-(AlxGa1−x)2O3 and metal-Ga2O3 contacts is important, since heat will be conducted through the metal-semiconductor interface as a preferred pathway to extract heat from the devices. In this work, we study the thermal transport across Al-(AlxGa1−x)2O3 and Al-Ga2O3 interfaces with an (010) orientation for the semiconductors. We have applied thermal and material characterization (time-domain thermoreflectance (TDTR) and high-resolution transmission electron microscopy (HRTEM) together with theoretical approaches to understand the interfacial thermal transport at Al-(AlxGa1−x)2O3 and AlGa2O3 contacts. It is found that for different growth methods, the highest TBC at Al-Ga2O3 interface occurs with molecular beam epitaxy (MBE) deposition of the Al on Ga2O3. However, the experimentally measured TBC at E-beam evaporated Al interfaces is much lower than that at the MBE grown Al interfaces. The measured values are also much lower than theoretical predictions, and it is related to the interfacial chemical reactions that occur at the interfaces. The effect of Al composition on interfacial thermal transport at Al/(AlxGa1−x)2O3 interface is also studied. It is found that the TBC at the E-beam evaporated Al/(AlxGa1−x)2O3 interface is very close to that of the E-beam evaporated Al-Ga2O3 interface at different temperatures in the ternary alloy studied.

G-Doping-Based Metal-Semiconductor Junction

Geometry-induced doping (G-doping) has been realized in semiconductors nanograting layers. G-doping-based p-p(v) junction has been fabricated and demonstrated with extremely low forward voltage and reduced reverse current. The formation mechanism of p-p(v) junction has been proposed. To obtain G-doping, the surfaces of p-type and p+-type silicon substrates were patterned with nanograting indents of depth d = 30 nm. The Ti/Ag contacts were deposited on top of G-doped layers to form metal-semiconductor junctions. The two-probe method has been used to record the I–V characteristics and the four-probe method has been deployed to exclude the contribution of metal-semiconductor interface. The collected data show a considerably lower reverse current in p-type substrates with nanograting pattern. In the case of p+-type substrate, nanograting reduced the reverse current dramatically (by 1–2 orders of magnitude). However, the forward currents are not affected in both substrates. We explained these unusual I–V characteristics with G-doping theory and p-p(v) junction formation mechanism. The decrease of reverse current is explained by the drop of carrier generation rate which resulted from reduced density of quantum states within the G-doped region. Analysis of energy-band diagrams suggested that the magnitude of reverse current reduction depends on the relationship between G-doping depth and depletion width.