Hot Complex Oxides--Turning up The Heat for Adsorption Control

It has long been known that molecular-beam epitaxy works best for materials that can be grown in an adsorption-controlled regime where thermodynamics automatically provides composition control. This is where MBE started—for GaAs and other compound semiconductors—and underlies its success for producing semiconductor films with the highest purity and mobility. The same holds for the growth of thin films of complex oxides by MBE, but the issue has been that it has not been possible to grow that many oxides in such a regime. In this talk I will describe how high substrate temperature opens the door to this desired growth regime for the growth of complex oxide thin films. Using a powerful CO₂-laser capable of heating to substrate temperatures of 2000 °C, we have grown an increasing number of complex oxides in an adsorption-controlled regime by MBE. In this talk I will show multiple examples, but concentrate on the growth and characterization of (Ba,Sr)TiO₃ films grown by MBE at substrate temperatures in the 1200-1500 °C range.