ZnO based heterostructures have potential interests both in the field of optoelectronics, where the very large binding energy of the excitons in ZnO should give rise to excitonic phenomena preserved well above room temperature, as well as in the field of spin electronics, where n- and p-type magnetic alloys are expected to present a ferromagnetic phase with a high curie temperature.
Since the first reports of MBE growth of single-crystalline ZnO epilayers in 1997, strong improvements in terms of crystal quality and morphology have been made. This first step make the intrinsic and extrinsic properties of this semiconductor more accessible than they used to be. Investigations on quantum heterostructures, alloys and doping are being carried out since the last 2-3 years.
In this talk, I will review these various achievements, underlining the following key issues : (i) strategy used for improved crystal and optical qualities, (ii) control of the epilayer polarity by using GaN buffer layers, (iii) residual and p-type doping and (iv) growth and properties of non magnetic and magnetic alloys.