Detecting the UV part of the spectrum is fundamental for a wide range of applications where ZnMgO has the potential to play a central role. The shortest achievable wavelength is a function of the Mg content in the films, which in turn is dependent on the growth technique. Moreover, increasing Mg contents lead to an electrical compensation of the films, which directly affects the responsivity of the photodetectors. In addition, the metal-semiconductor interface and the presence of grain boundaries have a direct impact on the responsivity through different gain mechanisms. In this work, we review the development of ZnMgO UV Schottky photodiodes using molecular beam epitaxy and spray pyrolysis, and we analyze and compare the physical mechanisms underlying the photodetector behavior.
We review in this paper the application of ZnO/(Zn,Mg)O quantum wells to the photodetection of the polarization state of UV light. This photodetection is achieved by using the natural anisotropy that exists in non-polar ZnO/(Zn,Mg)O quantum wells, which separates the excitonic absorption from the three valence bands to the conduction band depending on the incident light polarization. The device structures covered here consist of Schottky photodiodes on a- and m-plane orientations, grown by molecular beam epitaxy on ZnO or sapphire substrates, and are analyzed as a function of the incident light polarization.