Growth and thermal stability of GaPO4 epitaxial thin films

Abstract

Thin epitaxial films of gallium orthophosphate (GaPO4) are grown on α-quartz (SiO2) substrates. Here, amorphous stoichiometric precursor layers fabricated by pulsed-laser deposition on (001) SiO2 substrates are transformed to crystalline GaPO4 by postannealing in air at 650–950°C. Epitaxial films with thicknesses up to 300nm exhibit strong in-plane and out-of-plane textures (angular widths <0.6°). Long-term annealing in air at temperatures above the α- to β-phase transition of the quartz substrate (573°C) does not degrade the films.