Ultraviolet Electrically Injected Light Sources With Epitaxial ZnO- Based Heterojunctions

摘要

In this effort, significant emphasis was placed on the epitaxial growth and in situ doping of ZnO for optoelectronic devices. The materials research efforts on ZnO have resulted in device-quality material on sapphire substrates for the desired laser diodes, where the eventual material quality improvements necessary for the devices are anticipated for future growth on ZnO substrates. P-type doping of ZnO was demonstrated using nitrogen, though the p- type behavior was found to be unstable over time. In situ arsenic and antimony doping of ZnO was demonstrated, exhibiting either weak p-type behavior or mixed p-type/n-type conduction, though with stable behavior over time. In addition to the binary ZnO, the growth of MgZnO and ZnO/MgZnO heterojunctions was studied. Quantum wells exhibiting efficient radiative recombination were demonstrated. and may form the basis of future ultraviolet LEDs and lasers. Device applications of the ZnO/MgZnO materials were studied, which included studies of ohmic contacts to ZnO, UV photoconductors, and thin film transistors. The integration of ferroelectric oxide thin films with ZnO was also investigated, as a potential means of locally inverting ZnO to p-type, and to achieve novel multi-functional devices for reconfigurable systems.