Growth of thick $\varepsilon(\kappa)$-Ga$_2$O$_3$ films by halide vapor phase epitaxy

High crystalline quality epitaxial films of orthorhombic gallium oxide $\varepsilon(\kappa)$-Ga$_2$O$_3$ with a thickness of more 20 $\mu$m have been grown for the first time using halide vapor phase epitaxy. Sapphire wafers with preliminarily deposited GaN layers were used as substrates. The properties of the produced films are studied by X-ray diffraction and electron microscopy. The results are considered an important step towards obtaining thick layers and quasi-bulk $\varepsilon(\kappa)$-Ga$_2$O$_3$ crystals for practical applications in electronics and sensor technology.