Influence of the Substrate Temperature on the Texture of MgO Films Grown by Ion Beam Assisted Deposition

Abstract

AbstractThe variation in the substrate temperature during ion beam assisted deposition (IBAD), which employs the use of energetic ions to bombard a growing film, has been shown to influence the quality of crystalline texture in MgO films. Determining the acceptable deviation from the optimum ion to molecule ratio for different substrate temperatures establishes the optimum MgO deposition conditions. For each fixed deposition temperature, a set of samples was produced by varying the ion assist beam current from sample to sample while keeping the deposition rate constant. In this way, the ion to molecule ratio was modified and the range of achieving well textured films was determined. The investigation of the MgO texture dependence on the substrate temperature reveals that the best in-plane alignment is obtained at ˜ 25°C. At this temperature, MgO films with in-plane orientation distribution as low as 3.7° full width at half maximum (FWHM) have been attained. MgO films deposited at temperatures higher than 100°C have broad in-plane alignment. Although, the deposition at the lowest temperature (-150°C) did not improve the in-plane texture, the acceptable deviation from the optimum ion to molecule ratio for achieving biaxially textured films was the largest. As a trend, the acceptable ion to molecule deviation decreases with increasing substrate temperature. This is especially important for continuous IBAD MgO depositions where less restrictive conditions are desired.