Structural and optoelectronic characteristics of beta-Ga2O3 epitaxial films with Zn alloying and subsequent oxygen annealing

Pure and similar to 7.5 at% Zn alloyed beta-Ga2O3 epitaxial films were epitaxially grown by metal organic chemical vapor deposition choosing sapphire (c-plane) as substrates, followed by 600 degrees C annealing in an oxygen atmosphere. We have characterized the structural, optical and electrical properties of the four prepared samples including as-grown pure beta-Ga2O3, annealed pure beta-Ga2O3, as-grown beta-Ga2O3:Zn and annealed beta-Ga2O3:Zn films in detail. Furthermore, solar-blind UV photodetectors with metal-semiconductor-metal structures fabricated from these epitaxial thin films have been demonstrated. A giant performance enhancement can be observed for beta-Ga2O3 photodetectors by Zn alloying and subsequent oxygen annealing. The device fabricated from the annealed beta-Ga2O3:Zn film shows a low dark current of similar to 3.7 x 10(-11) A, a high responsivity of 2.8 x 10(3) A W-1 and a high UV-vis rejection ratio of 5.6 x 10(5) at 10 V bias. And an ultra-high specific detectivity up to 5.9 x 10(16) cm Hz(1/2) W-1 (Jones) is observed. Such excellent photodetection performance of annealed Ga2O3:Zn devices can be explained by the donor compensation effect and the deep level trap removal effect by the introduction of Zn. Our findings contribute a roadmap for realizing high-performance Ga2O3-based solar-blind photodetectors, and provide a sturdy foundation for future applications.