Pulsed Laser Deposition 2: Heteroepitaxial Growth of Ga$$_2$$O$$_3$$ and Related Alloys

We review heteroepitaxial growth of Ga\(_2\)O\(_3\) and related alloys by pulsed laser deposition (PLD). First, we briefly summarize the history of PLD and discuss its evolution and development since its breakthrough in the 1980s with the focus on combinatorial material synthesis. Then, the impact of strain on the lattice constant of rhombohedral, pseudomorphic (Al, Ga)\(_2\)O\(_3\) thin films is introduced and the determination of thin film composition from X-ray diffraction measurements is outlined. For monoclinic Ga\(_2\)O\(_3\) layers the influence of key growth parameters on growth rate and surface morphology is discussed. Electrical transport properties of monoclinic thin films doped by silicon or tin are presented and compared to that of homoepitaxial layers. For ternary thin films growth parameters strongly influence the chemical composition in addition to growth rate and morphology. High oxygen pressures and/or low growth temperatures are necessary for a stoichiometric transfer of the target composition to the epilayer which is explained by the desorption of gallium suboxides occurring otherwise. Further, we resume solubility limits and the dependence of structural, optical and vibrational properties on the alloy composition of monoclinic (In, Ga)\(_2\)O\(_3\) and (Al, Ga)\(_2\)O\(_3\) thin films.