Engineering strain and conductivity of MoO ₃ by ion implantation

α-MoO ₃ lamellar crystals are implanted with 170 keV oxygen ions at room temperature and with fluences between 1 × 10 ¹² cm ⁻² and 1 × 10 ¹⁷ cm ⁻² , in order to modify the electrical and structural properties of the crystals. A controllable and significant increase of the electrical conductivity, over several orders of magnitude, is observed after implantation at high fluences. Based on high resolution X-ray diffraction (HRXRD) and micro-Raman spectroscopy measurements, this effect is attributed to the formation of donor-type defect complexes and new phases more conductive than the α-MoO ₃ orthorhombic phase. A significant expansion of the b lattice parameter, increasing with fluence, is observed as a response to the defects created by implantation. Strain build-up occurs in several steps and in distinct depth regions within the implanted layer. Contrary to the typical values reported for other implanted oxide materials, an unusually high maximum perpendicular deformation of ∼3% is verified.