Very thin carbon films were deposited by electron beam-plasma vacuum deposition technique on quartz and sapphire substrates. The concentration of elements was determined by RBS and ERD analytical method simultaneously. Concentrations of elements were practically the same for all samples. Raman spectroscopy and deconvolution of Raman spectra was used for chemical structural features determination of carbon films. Raman spectroscopy results showed that films contained several carbon phases. The photo-induced electron emission characteristics of very thin carbon films on quartz and sapphire substrates as back-side illuminated transmission photocathode are discussed. Best electron emission properties exhibit transmission photocathode with very thin carbon film prepared on sapphire substrate at lower substrate temperature.
An optimization of electrical, thermal, and mechanical properties of SiC MOSFET transistors supported by advanced effective 3-D electro-thermal device simulation is presented. The developed simulation method is capable of a full analysis of complex structures with a high speed of simulation and simple implementation. The simulation method is utilized for electrical and thermal analysis of power SiC MOSFET. Two bonding methods of SiC MOSFET transistor are analyzed and compared. Simulation results demonstrated that the optimized clip-bond concept has better electrical and thermal performance than the wire-bond.
This paper investigates the robustness and reliability issues of commercial 1.2-kV 4H-SiC MOSFETs under repetitive unclamped inductive switching (UIS). The degradation of device characteristics, including the transfer characteristics, drain leakage current $I_{dss}$ , and output characteristics, is observed. A significant increase in leakage current was observed after relatively short avalanche stress (UIS stress), and device destruction occurred after 30 million of cycles. Besides the shift of static electrical characteristics, also a change in switching times was observed. The hot carriers injection and trapping into the gate oxide and its interfaces is believed to be responsible for the variation of electrical parameters.
Incremental capacity analysis (ICA) and Galvanostatic Intermittent Titration Technique (GITT) are commonly used tools of electrical characterisation of degradation of Li-ion batteries. Disadvantage of these methods is their significant time consumption since both of these methods are based on charging/discharging by very low currents (e.g. C/20). In this contribution we propose a novel approach of performing ICA analysis via utilisation of GITT data in order to significantly decrease time of the measurements and/or include ICA analysis into GITT measurements, which would not be otherwise performed.
This paper presents the practical solutions for measuring small currents at the characterization of organic field-controlled transistors. It presents the design, PCB layout, and methodology of various small current measurement principles. The design mainly focuses on a trans-impedance amplifier that transforms current into voltage. In this paper, we can also determine the critical parameters for selecting the main components in the measuring part. Also, simulations and measurement of real measured parameters with an evaluation of all critical quantities, such as accuracy, precision, linearity, offset, noise, and response speed.
