SiC thin films

for

high temperature applications

Sateesh.prathapani11 ETMM 11

M Tech materials EngineeringSchool of Engineering sciences & Technology

University Of Hyderabad

OUTLINE: Introduction Characteristics of SiC Fabrication Applications

INTRODUCTION What is SiC:

Silicon carbide (SiC) is a wide bandgap semiconductor (3 eV) material that shows great promise in high power and high temperature electronics applications because of its high thermal conductivity and high breakdown electrical field.

Why is it so Important:

The increasing demand for MEMS as, for example, piezoresistive sensors with capabilities of operating at high temperatures, mainly for automotive, petrochemical and aerospace applications, has stimulated the research of alternative materials to silicon in the fabrication of these devices.

How is it Important:

Devices which operate at high speeds, at high power levels are to be used in extreme environments at high temperatures and high radiation levels need materials with wider bandgaps.

There fore the modern electronics which depend on Si, are replaced by SiC which have these desired characteristics.

SPECIAL CHARACTERISTICS

excellent electrical characteristics - wide bandgap (3 eV)

high breakdown field strength (10 times higher than Si)

low intrinsic carrier concentration which allow stable electronic properties under harsh environments

SiC exhibits high elastic modulus at high temperatures

all these properties of SiC materials make them very attractive for MEMS (piezoresistive sensors) applications

COMPARISON OF SEMICONDUCTOR CHARACTERISTICS

property Si GaAs β-SiC

Maximum operating Temperature(°C)

300 460 873

Bandgap (eV)at 300 K

1.1 1.4 2.3

Physical stability

Good Fair Excellent

Breakdown field, Eb

(106 V/cm) 0.3 0.4 4

Dielectric constant 11.8 12.8 9.7

Thermal conductivity(W/cm-°C)

1.5

0.5 5

SILICON CARBIDE THIN FILMS FOR PIEZORESISTIVE SENSORS APPLICATIONS

Piezoresistivity is a physical property which has been widely used to convert a mechanical signal into an electrical one, in different device types.

such as pressure sensors,

accelerometers,

strain gauges and flow sensors

This Piezoresistivity property is quantified in terms of gauge factor (GF), which is defined as the fractional change in the resistance per unit strain

Gauge Factor (GF) = (ΔR/R)/ε

APPLICATIONS Many space and terrestrial applications have

a requirement for wide bandgap materials.

SiC also has great potential for high power and frequency operation due to a high saturated drift velocity

Optoelectronic applications-blue LED and ultraviolet photodetectors.

Gas sensing

Telecommunications