Effect of Alpha Particles on the Electrical Characteristics of the MIS: Au-Ta2O5-GaAs Devices

Abstract

The paper aims to study the effect of alpha particles on the electrical properties of the MIS:(Au-Ta₂O₅-GaAs) device and on the electrical current transition mechanism. The device is prepared by deposing a layer of gold with thickness 1000A by using the thermal evaporation method under pressure of 10^-5 torr to form the upper gate of the construction MIS. The prepared devices are irradiated with alpha particles from the source ²²⁶ Ra (1 mCi). The irradiation is performed under room temperature with alpha energies (5.1, 4, 3, 1.8 &1.2) for different times from (0-30) min. The irradiation solid angle was small to maintain the alpha particles normally incident on the device. The maximum energy 5.1 MeV of alpha particle is attenuated to lesser energies by situating polymer sheets with different thickness in the front of the incident particles. The energy loss and the range of alpha particles within the layers of the device, the gold (Au), the tantalum oxide(Ta2O5) and the Gallium arsenide(GaAs), are calculated to determine the way of losing the alpha particle of their energies, the amount of the produced damage and the point where the maximum energy loss is taking place within the device. The irradiation showed an effect on the electrical properties of the device, and this effect is found to be varied with the particles energy and the irradiation time. The I-V characteristics showed that the current transition mechanism is Shotcky for most of the cases of irradiation and Pol-Frenkle for some cases. These characteristics also showed a permanent damage in the device at energies (5.1 & 1.2), and a temporary effect at energies of 4 MeV, while there is no a significant effect at energies (1.8 &3) MeV.