Development of a Leakage Current Meter for the Evaluation of MOSFETs in Radiation-Intensive Environment


Metal-Oxide-Semiconductor-Fieldeffect-Transistors (MOSFETs) are one of the main transistor types, that are used in power electronics. Their fields of application are diverse, mainly in the conversion of ac voltage to dc voltage and vice versa or dc to dc voltage.

Their main materials are currently silicon (Si) and silicon carbide (SiC) and recently also gallium nitride (GaN), which provides good characteristics in terms of high switching frequencies, low conducting losses and high breakdown voltages.

However, they suffer from great dependencies due to environmental influences, such as the ambient temperature, drain-source voltages and radiation influence.

If semiconductors are used for example in airplanes or particle accelerators, it is necessary to protect them from incoming radiation, such as neutrons. In these environments they are more susceptible to the effects of ionizing radiotion, particularly the effect ‘Single Event Effect’ produced by neutrons. These events can lead to a destruction of semiconductors, thus it is necessary to shield them properly.

One method to shield and protect electronics is to use a material, that is able to absorb neutrons, for example Boron Carbide (B4C) or Boron Nitride (BN). In order to detect SEEs, one can measure the leakage current in MOSFETs, which is increasing, if a neutron detonates onto the chip area of the device.

The main aim of this thesis is to develop a current meter, that is able to detect the leakage current in MOSFETs. In order to compare shielded and non-shielded electronics, a housing made of B4C is to develop, which protects them from incoming radiation. The printed circuit board (PCB) will contain several MOSFETs in order to predict the probability of a failure of a Si-MOSFET.

Moreover, it is necessary to track the data during a test procedure. Thus, the data will be tracked via a microcontroller and is places on a storage device.

A code is to develop, that transmits the analog data into digital data using a controller area network bus (CAN).