Study of gamma-ray radiation effects on the passivation properties of atomic layer deposited Al 2 O 3 on silicon using deep-level transient spectroscopy

Aluminum oxide (Al2O3) has emerged as a potential dielectric material and exhibited an excellent passivation property on silicon surface. However, such oxide layer is extremely sensitive to γ-ray irradiation. In this work, deep-level transient spectroscopy has been applied to study the influence of γ-ray irradiation on the passivation properties of atomic layer deposited Al2O3 on silicon. It is shown that γ-ray irradiation leads to a significant increase of interface state density (Dit). Meanwhile, its energy distribution is broadened and shifts deeper with respect to the top of valence band, and therefore evolves into more efficient recombination centers for carriers. Besides, capacitance–voltage (C–V) curves shows a progressive shift toward the negative voltages with increased radiation doses. This indicates the hole trapping in Al2O3, which can neutralize the negatively charged defects and therefore degrade its field-effect passivation. Hence, the passivation quality of Al2O3 on silicon deteriorates significantly after γ-ray radiation.