Homoepitaxial growth of SrTiO3 by Pulsed Laser Deposition: energetic vs thermal growth

The role of energetic processes in homoepitaxial growth of SrTiO3 (STO) by Pulsed Laser Deposition (PLD) was studied via Real-Time X-ray scattering. Two process were developed, an energetic process and a thermal process. Both processes utilized a background gas of 2 mTorr of O2. The thermal process had an additional 300 mTorr of Helium to act as a buffer gas. Langmuir probe measurements verified the energies of the two process to be between 50-100 electron-volts (eV) and 0.02-0.05 eV respectively. Specular X-ray reflectivity, sensitive to inter-layer transport of material, was the same for both processes. Diffuse scattering, sensitive to the in-plane transport of material, was markedly different. In both processes, lobes of scattering as a function of Qr arise, reaching a maximum intensity at each half layer of growth. The energetic process has a broader peak at a higher Qr. Both data sets collapse to a common curve upon scaling the axes, suggesting a similar island distribution on different length scales