Optically Switched Graphene/4H-SiC Junction Bipolar Transistor (G-SiC BJT)

Reference #: 01129

The University of South Carolina is offering licensing opportunities for a novel bipolar transistor junction that is highly sensitive to UV light and useful for detection devices such as flame detectors, spectrometers, and missile tracking systems. The transistor may also be adopted for power electronic systems.

Invention Description:

The subject invention is a graphene/4H-Sic junction bipolar transistor (G-SiC BJT) designed to detect ultraviolet and nuclear radiation. It uses a highly transparent graphene layer to provide a low-loss radiation window while the transistor’s structure converts incoming radiation into an electric current and amplifies it more than 300 times to a useable level.

Potential Applications:

• Ideal for detection applications that require high sensitivity to UV light, such as flame sensing, spectroscopy, astronomy, and missile tracking;
• Other UV applications including lamps for sterilization, curing, tanning, and water purification systems;
• Also applicable in power electronic systems that require large current densities including hybrid and electric vehicles, locomotive traction, and HVDC transmission for power grids.

Advantages and Benefits:

1. The SiC substrate’s radiation hardness and low leakage current extends the lifetime of the device and enables high sensitivity detection, respectively.
2. The graphene layer’s transparency (97.7% irrespective of wavelength) to electromagnetic radiation makes it the best choice for the illumination window.
3. Built-in amplification eliminates the need of a separate amplifier stage, which is used in conventional detectors for boosting the low output signal to a usable level.
4. The graphene/SiC junction significantly reduces the complexity and cost of the fabricating of a SiC transistor, rendering an intrinsically defect-free, reproducible  material interface, which improves device reliability.

Background:

Existing radiation and UV photo-detectors use a photodiode structure, the sensitivity of which is constrained by background noise and has no internal gain. The built-in bipolar gain in G-SiC BJT overcomes these noise limitations and rivals gain values for conventional SiC bipolar junction devices. This device offers simplicity of design and higher quality interface between material layers.

Development:

An optically activated G-SiC BJT prototype has been fabricated and characterized in both active and reverse active modes.