Physics Seminars
Radiation Effects in Wide Bandgap Semiconductors and Novel Radiation Sensor Designs
Speaker: Katharina Lorenz (Instituto de Engenharia de Sistemas de Computadores Microsystems and Nanotechnology (INESC MN)-Portugal)
Date: Wednesday 22 November 2023
Time: 15:00
Venue: Queens Building N3.28
Wide bandgap semiconductors (WBS) enable electronic devices to operate at high power and high temperature. Moreover, many WBS are considered more radiation-resistant than conventional semiconductors such as Si or GaAs, making them interesting for applications in extreme radiation environments and for radiation sensing. Benefiting from the remarkable radiation resistance of GaN, we developed radiation sensors based on single GaN microwires. Their potential for the detection of ionising radiation, as well as their degradation upon high fluence ion irradiation, will be discussed. Fig. 1 shows a Scanning Electron Microscopy (SEM) image of a microwire device based on a p-n core-shell structure. Of particular interest is the possibility of using these devices in self-powered mode, without any externally applied bias [1]. Ga2O3 is another emerging WBS. The doping of Ga2O3 with optically active chromium ions enables radiation sensing based on optical detection. Irradiating Cr-doped Ga2O3 with MeV protons was shown to activate the red-infrared light emission of Cr3+, while quenching the intrinsic ultraviolet-blue luminescence. Fig. 2 shows the corresponding change of colour from blue to red of the ion-beam-induced luminescence with the increasing proton fluence. Besides the in situ optical monitorisation of the radiation dose, post-irradiation read-out by photo- and thermoluminescence was also demonstrated [2, 3]. [1] D. Verheij et al., Appl. Phys. Lett. 118, 193501 (2021). [2] M. Peres et al., Appl. Phys. Lett. 120, 261904 (2022). [3] D. M. Esteves et al., Scientific Reports 13, 4882 (2023).