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Proton irradiation-induced effects on AlGaN/GaN high electron mobility transistors (HEMTs) were studied by emulating a certain space radiation environment (upstream of the earth's bow shock) using a relatively low energy (100 keV) proton beam with fluences of 1 × 1010, 1 × 1012, and 1 × 1014 protons/cm2. In order to isolate radiation-induced effects produced by the modification of the epi-layer from the effects produced by the change in the device structure (such as contacts), the epi-layers were irradiated prior to device fabrication, followed by material/device characterization. Proton irradiation-induced sub-gap traps were detected by spectroscopic photo current-voltage measurement. Raman study revealed that the proton irradiation had induced strain relaxation on the AlGaN/GaN HEMTs epi-layer. No substantial change in the crystal quality of the epi-layer was indicated by Raman and PL studies. With increasing proton fluences, increasing charge carrier density was observed, which was estimated via Raman spectroscopy and the charge-control model analysis. The magnitude and direction of the transistor threshold voltage shift were also dependent on proton fluence. Overall, degradation of transistor output characteristics of the fabricated HEMTs was observed with increasing proton fluence. However, based on the observed performance and the level of influence on material/device characteristics by 100 keV protons, it can be suggested that the AlGaN/GaN HEMTs have high endurance for exposure to relatively high fluences of the low-energy proton beam. [ABSTRACT FROM AUTHOR]

It is critical to understand the laws of quantum mechanics in transformative technologies for computation and quantum information science applications to enable the ongoing second quantum revolution calls. Recently, spin qubits based on point defects have gained great attention, since these qubits can be initiated, selectively controlled, and read out with high precision at ambient temperature. The major challenge in these systems is controllably generating multiqubit systems while properly coupling the defects. To address this issue, we began by tackling the engineering challenges these systems present and understanding the fundamentals of defects. In this regard, we controllably generate defects in MoS 2 and WS 2 monolayers and tune their physicochemical properties via proton irradiation. We quantitatively discovered that the proton energy could modulate the defects' density and nature; higher defect densities were seen with lower proton irradiation energies. Three distinct defect types were observed: vacancies, antisites, and adatoms. In particular, the creation and manipulation of antisite defects provides an alternative way to create and pattern spin qubits based on point defects. Our results demonstrate that altering the particle irradiation energy can regulate the formation of defects, which can be utilized to modify the properties of 2D materials and create reliable electronic devices.