The Varadis RADFET is a microelectronic chip, specially engineered to be sensitive to high energy (ionising) radiation. The RADFETs are small, robust, require no power to detect radiation, can easily be integrated into electronic systems, and are cost effective.
Varadis RADFET VT01
400nm RADFET in Six Lead SOT-23 Plastic Package
For doses between 1 cGy (1 rad) and 1 kGy (100 krad)
RADFET is a discrete p-channel MOSFET optimized for radiation sensitivity. RADFETs are sensitive to ionizing radiation: gamma rays, X-rays, and protons.
The critical region of the RADFET is its gate oxide. Through generation and trapping of radiation-induced charges in the gate oxide, radiation exposure changes the output voltage of the RADFET and this change is related to the radiation dose. The RADFET response is non-linear and a pre-recorded calibration curve is used to read the dose. The read-out is done by forcing a DC current (in the range of 10s of μA) into the device and measuring the DC voltage (in the range of 0.5 to 8 Volts).
Varadis RADFET VT02
400nm RADFET in Eight Lead Ceramic Side Braze Package
For doses between 1 cGy (1 rad) and 1 kGy (100 krad)
RADFET is a discrete p-channel MOSFET optimized for radiation sensitivity. RADFETs are sensitive to ionizing radiation: gamma rays, X-rays, and protons.
The VT02 is used by organisations such as the European Space Agency and a number of other space agencies across the globe. The VT02 is hermetically sealed and slightly larger than the plastic version.
The critical region of the RADFET is its gate oxide. Through generation and trapping of radiation-induced charges in the gate oxide, radiation exposure changes the output voltage of the RADFET and this change is related to the radiation dose. The RADFET response is non-linear and a pre-recorded calibration curve is used to read the dose. The read-out is done by forcing a DC current (in the range of 10s of μA) into the device and measuring the DC voltage (in the range of 0.5 to 8 Volts).
Important Information: The VT01 & VT02 RADFETs have a large dynamic range, from 1 cGy (1 rad) to 1 kGy (100 krad). To fully understand capabilities and limitations of these products, please review datasheets available on this web page.
Varadis RADFET VT03
1μm RADFET in Six Lead SOT-23 Plastic Package
For doses between 3 mGy (0.3 rad) and 10 Gy (1 krad)
RADFET is a discrete p-channel MOSFET optimized for radiation sensitivity. RADFETs are sensitive to ionizing radiation: gamma rays, X-rays, and protons.
The VT03 addresses a lower dose range than either VT01 or VT02.
The critical region of the RADFET is its gate oxide. Through generation and trapping of radiation-induced charges in the gate oxide, radiation exposure changes the output voltage of the RADFET and this change is related to the radiation dose. The RADFET response is non-linear and a pre-recorded calibration curve is used to read the dose. The read-out is done by forcing a DC current (in the range of 10s of μA) into the device and measuring the DC voltage (in the range of 5 to 9 Volts).
RADFET Reader PRO
For measuring the output voltage of RADFET
The RADFET Reader PRO is a hand-held, battery-operated instrument designed for measuring the output voltage of Varadis RADFETs.
Built on a novel technology currently used in space applications, the RADFET Reader PRO offers the convenience and cost benefits of passive systems but with the added value of active dosimetry and the functionality of more expensive, bulkier devices.
Compatible with the following Varadis products:
The Varadis 400nm RADFET
The Varadis 100nm RADFET
The Varadis 1μm RADFET
VT01 RADFET Readout Module RM-VT01
For optimized RADFET read-out
The RM-VT01 RADFET Read-out Module is a result of many years of experience of Varadis engineers in designing RADFET read-out circuitry.
Aimed at providing an optimized RADFET read-out and cutting customers’ development time and cost, the RM-VT01 contains the VT01 RADFET and key circuitry for its readout. The module outputs a buffered analog voltage (RADFET threshold voltage), which is related to accumulated radiation dose of the RADFET.
Due to its small size, RM-VT01 can easily be integrated into customer’s system by soldering directly onto the PCB or via a standard through-hole header connector. The threshold voltage of the RADFET is buffered for easier integration with standard analog to digital converters, significantly simplifying customer’s electronics design. Both Read-out and Irradiation (sense) modes of RADFET operation are supported. The user can easily select the desired mode by TTL logic level control signals.
Additional RADFET Products
In addition to the VT01 and VT02 Varadis 400nm and VT03 Varadis 1μm RADFETs, we offer a Varadis 100nm RADFET suitable for the highest doses, up to 10kGy and even beyond.
The exact dose ranges will depend on the customer’s application requirements and the design of readout circuitry.
Please contact us for more information on these products.
Varadis Supporting Documentation
RADFET VT01 (Datasheet)
RADFET VT02 (Datasheet)
RADFET VT03 (Datasheet)
RADFET Reader PRO (Manual)
VT01 RADFET Readout Module (Datasheet)
Additional RADFETs Overview