Two Packaging Solutions for High Temperature SiC Diode Sensors

IEEE J. Electron Devices Soc.

Draghici

et al. 2020

Self Cite

A practical model, adequate for full reproduction of inhomogeneous Schottky diodes' forward characteristics over wide high-temperature and bias ranges, is proposed. According to this p-diode model, the Schottky contact current is considered to flow through m parallel-connected internal diodes, each with stable, constant barrier height and specific series resistance (both main model parameters). The value of m, required to reproduce the entire electrical forward behavior of a non-uniform Schottky contact, is directly connected to a particular model parameter (peff), used to define the inhomogeneity degree. The p-diode model was tested on forward characteristics measured for both Ni and commercial Ti Schottky diodes on 4H-SiC, which exhibited varying degrees of inhomogeneity. Excellent replication of experimental curves was achieved for all investigated samples, even those with obvious irregularities, such as "humps", explained in the model by the series resistances' influence. In the case of m=1, the proposed model does not produce identical results with the conventional model of a homogeneous Schottky contact if peff ≠ 0. The value of this parameter indicates how much of an inhomogeneous contact's area is essentially used for current conduction.

Section: Results Discussionmentioning

confidence: 99%

Enhanced Non-Uniformity Modeling of 4H-SiC Schottky Diode Characteristics Over Wide High Temperature and Forward Bias Ranges

IEEE J. Electron Devices Soc.

Draghici

et al. 2020

Self Cite

“…Explicitly, biasing the diode at constant currents leads to a quasi-linear decrease in voltage as temperature rises. The sensitivity is inversely proportional to the current level [6,7,8,9,10,11].…”

Section: Methodsmentioning

confidence: 99%

“…Temperature sensors are required in virtually all monitoring applications, irrespective of investigated settings [1]. As advancements in regulations targeting the minimization of industrial impact on the environment are carried out, precise temperature control and energy efficiency have become essential research topics, which exert ever-growing standards from temperature sensors [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]. This aspect works in tandem with the fact that most industrial processes demand careful monitoring of temperature levels in order to ensure optimal quality and yield [1,6].…”

Section: Introductionmentioning

confidence: 99%

“…As such, wide band-gap semiconductor-based temperature sensors have become a promising alternative for harsh industrial applications [2,3,4,5,6,7,8,9,10,11,12,13,14,15]. Silicon carbide (SiC) is a particularly suitable material due to its mechanical robustness, radiation, chemical inertness, and high bandgap (E g = 3.25 eV for 4H-SiC), which allows fabricated devices to operate at temperatures up to 400 °C or more [2,3,4,5,6,7,8,9,10,11,12,13,14,15]. Among all devices fabricated on SiC (PN, PIN, JFET, etc.…”

Section: Introductionmentioning

confidence: 99%

“…Among all devices fabricated on SiC (PN, PIN, JFET, etc. ), Schottky diodes are the most cost-effective and technologically mature, with considerable commercial success in power and sensing applications [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27]. Hence, due to their simple structure, very compact size and quasi-linear voltage-temperature dependence (with sensitivities exceeding 2 mV/°C), SiC Schottky diodes are excellent candidates for high-temperature monitoring in hostile industrial environments [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,18,19,20,21,22,23,24].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

400 °C Sensor Based on Ni/4H-SiC Schottky Diode for Reliable Temperature Monitoring in Industrial Environments

Draghici

et al. 2019

Sensors

Self Cite

This paper presents a high-temperature probe suitable for operating in harsh industrial applications as a reliable alternative to low-lifespan conventional solutions, such as thermocouples. The temperature sensing element is a Schottky diode fabricated on 4H-SiC wafers, with Ni as the Schottky metal, which allows operation at temperatures up to 400 °C, with sensitivities over 2 mV/°C and excellent linearity (R2 > 99.99%). The temperature probe also includes dedicated circuitry for signal acquisition and conversion to the 4 mA–20 mA industrial standard output signal. This read-out circuit can be calibrated for linear response over a tunable temperature detection range. The entire system is designed for full electrical and mechanical compatibility with existing conventional probe casings, allowing for seamless implementation in a factory’s sensor network. Such sensors are tested alongside standard thermocouples, with matching temperature monitoring results, over several months, in real working conditions (a cement factory), up to 400 °C.

A model to non-uniform Ni Schottky contact on SiC annealed at elevated temperatures

Applied Physics Letters

Bădilă

et al. 2015

Ni Schottky contacts on SiC have a nonideal behavior, with strong temperature dependence of the electrical parameters, caused by a mixed barrier on the contact area and interface states. A simple analytical model that establishes a quantitative correlation between Schottky contact parameter variation with temperature and barrier height non-uniformity is proposed. A Schottky contact surface with double Schottky barrier is considered. The main model parameters are the lower barrier (ΦBn,l) and a p factor which quantitatively evaluates the barrier non-uniformity on the Schottky contact area. The model is validated on Ni/4H-SiC Schottky contacts, post metallization sintered at high temperatures. The measured IF–VF–T characteristics, selected so as not to be affected by interface states, were used for model correlation. An inhomogeneous double Schottky barrier (with both nickel silicide and Ni droplets at the interface) is formed by a rapid thermal annealing (RTA) at 750 °C. High values of the p parameter are obtained from samples annealed at this temperature, using the proposed model. A significant improvement in the electrical properties occurs following RTA at 800 °C. The expansion of the Ni2Si phase on the whole contact area is evinced by an X-Ray diffraction investigation. In this case, the p factor is much lower, attesting the uniformity of the contact. The model makes it possible to evaluate the real Schottky barrier, for a homogenous Schottky contact. Using data measured on samples annealed at 800 °C, a true barrier height of around 1.73 V has been obtained for Ni2Si/4H-SiC Schottky contacts.