They are the key component used to make short-wavelength (green-UV) LEDs or lasers, and are also used in certain radio frequency applications, notably military radars.
Their intrinsic qualities make them suitable for a wide range of other applications, and they are one of the leading contenders for next-generation devices for general semiconductor use.
Additionally, most wide-bandgap materials also have a much higher critical electrical field density, on the order of ten times that of conventional semiconductors.
Combined, these properties allow them to operate at much higher voltages and currents, which makes them highly valuable in military, radio, and power conversion applications.
[3] Most wide-bandgap materials also have high free-electron velocities, which allows them to work at higher switching speeds, which adds to their value in radio applications.
A single WBG device can be used to make a complete radio system, eliminating the need for separate signal and radio-frequency components, while operating at higher frequencies and power levels.
However, their clear inherent advantages in many applications, combined with some unique properties not found in conventional semiconductors, has led to increasing interest in their use in everyday electronic devices instead of silicon.
For instance, at room temperature most metals have a series of partially filled bands that allow electrons to be added or removed with little applied energy.
Reversing the polarity of this applied energy pushes the electrons into the more widely separated bands, making them insulators and stopping the flow.
However, this switching process depends on the electrons being naturally distributed between the two states, so small inputs cause the population statistics to change rapidly.
As the external temperature changes, due to the Maxwell–Boltzmann distribution, more and more electrons will normally find themselves in one state or the other, causing the switching action to occur on its own, or stop entirely.
In the opposite process, when excited electron-hole pairs undergo recombination, photons are generated with energies that correspond to the magnitude of the bandgap.
At the point of breakdown, electrons in a semiconductor are associated with sufficient kinetic energy to produce carriers when they collide with lattice atoms.
Intervalley scattering is an additional scattering mechanism at large electric fields, and it is due to a shift of carriers from the lowest valley of the conduction band to the upper valleys, where the lower band curvature raises the effective mass of the electrons and lowers electron mobility.
Silicon and other common materials have a bandgap on the order of 1 to 1.5 electronvolt (eV), which implies that such semiconductor devices can be controlled by relatively low voltages.
The high breakdown voltage of wide-bandgap semiconductors is a useful property in high-power applications that require large electric fields.
Due to its robustness and ease of manufacture, silicon carbide semiconductors are expected to be used widely, creating simpler and higher efficiency charging for hybrid and all-electric vehicles, reducing energy loss, constructing longer-lasting solar and wind energy power converters, and eliminating bulky grid substation transformers.
Devices based on wide bandgap materials are capable of switching at much higher frequencies than silicon versions.
As a result, higher voltages and more sensitive current measurements are required to properly characterize the WBG semiconductor during testing.
[20][21] Broadband semiconductor power devices require multiple measurements including on and off state, capacitive voltage and dynamic characteristics.