Florin Draghici

An industrial temperature probe based on SiC diodes

A temperature probe based on 4H-SiC Schottky diodes is proposed. These diodes have been fabricated and characterized for temperature sensor applications. A conversion circuit to 4–20mA output current for ambient to maximum (400°C) input temperature was designed and tested.

A system to measure reverse recovery time and stored charge at ultrafast power diodes

This paper presents a reverse recovery time (t/sub rr/) and stored charge (Q/sub rr/) measurement circuit for ultrafast Si and SiC power diodes. The circuit developed according to the JESD24-10 standard specification allows one to obtain 0.1-5 A forward current, 10-100 V reverse voltage and 50-500 A//spl mu/s di/dt.

Two Packaging Solutions for High Temperature SiC Diode Sensors

A partially electrically isolated package with a gold wire and fully isolated solution with a metallic piston, respectively, are designed and tested for high temperature sensors (400°C) based on SiC Schottky barrier diodes (SBD). Electrical behavior and sensor performance are very close for both packaging solutions. The stress due to contact pressure and higher cost are some disadvantages for pressure contact technology.

High temperature sensor based on SiC Schottky diodes with undoped oxide ramp termination

A simple technology of 4H-SiC Schottky diode with oxide ramp termination is presented. The ramp is controlled by two undoped layers: an annealed (compact) oxide layer and as deposited layer, respectively.

Temperature behavior of 4H-SIC MOS capacitor used as a gas sensor

Temperature behavior of 4H-SiC MOS capacitor is investigated. A new layout with several active MOS structures is proposed. Measured C-V characteristics show good thermal stability up to 300 C. The main electrical parameters of the MOS structure have been extracted by measurements on wafer and encapsulated samples.

A SPICE model for electroluminescent foils

Electroluminescent lamps are used today as backlight for displays, inclusive in luxury cars or can be used for different type of signaling in airplanes or in advertising industry. One of the drawbacks of them, beside the limited lifetime and poor light efficiency is the special power supply circuit that is necessary to drive the lamps. In order to make advantage of simulation tools for inverters design a SPICE like model is very useful. In this work we have tried to develop a “natural” electric model based on EL construction and on experimental investigations.

Electrical Characterization of Ni-Silicide Schottky Contacts on SiC for High Performance Temperature Sensor

The electrical behavior and stability of a temperature sensor based on 4H-SiC Schottky diodes using Ni2Si as Schottky contact, are investigated. The ideality factor and the barrier height were found to be strongly dependent on the post-annealing temperature of the Ni contact (which lead to the formation of Ni2Si). A nearly ideal Schottky device, with the barrier height approaching the high value of 1.7eV, and a slight temperature dependence, was obtained after an annealing at TA=800°C. This high barrier height proves that Ni2Si is suitable as Schottky contact for temperature sensors, able to reliably operate up to 450°C. Sensor sensitivity levels between 1.00mV/°C and 2.70 mV/°C have been achieved.

High Temperature Hydrogen Sensor Based on Silicon Carbide (SiC) MOS Capacitor Structure

MOS capacitor devices based on silicon carbide (SiC) are largely used as hydrogen detectors in high temperature and chemically reactive environments. A SiC MOS capacitor structure used as hydrogen sensor is analyzed by extensive simulations. The sensitivity to hydrogen detection, stability to temperature variation and dependence on interface states concentration are evaluated. The effects of structure parameters on sensors performance are also investigated. Results show that the oxide layer type and thickness and the SiC polytype have a significant influence on the detectors performance. The proposed optimum structure for high temperature hydrogen detection is based on 3C-SiC substrate and 10nm TiO2 layer. In accordance with the simulations results, three types of masks are designed for the fabrication of SiC MOS capacitor structures.

High temperature characterization system for silicon carbide devices

In this paper it is described a design technique used to collect and analyse power devices characteristics in high temperatures domain. Following this technique, a complete hardware and software platform is built for thermal characterization of power devices.

A Fully Electrically Isolated Package for High Temperature SiC Sensors

A fully electrically isolated package for a SiC temperature sensor, able to work at high temperature, is presented in this paper. The adopted packaging solution was tested under thermal stress by varying the temperature between 300C and 400C (for 500 cycles) and between 50C and 400C (for other 500 cycles). The thermal stress had negligible effect on the capsules leakage currents (measured from the sensor terminals to the package metal casing) and did not degrade the glass which ensures the sealing of the capsule. The measurements and microphysical investigations showed a stable operation of the package up to temperatures of 400C.