Development of Passivation Technology for Improved GaN/AlGaN HEMT Performance and Reliability

摘要

Under the support of this contract, we have been successful in mitigating the current collapse that is found in nitride based high electron mobility transistors (HEMTs) that is responsible for low power performance from these devices. We have successfully and repeatedly grown oxide material that, along with surface cleaning recipes, reduce the surface states and reduce the device-device surface leakage. As part of the recipe development we have studied fundamental characteristics of the native oxides on GaN and AlGaN surfaces using XPS and compared the results to oxides generated by exposure to UV ozone, We have developed a lattice matched oxide, magnesium calcium oxide (M8CaO), and deposition recipe that provides for the lowest level of surface traps and thus the highest level of surface passivation. Along with this oxide, we have shown that a thin layer of scandium oxide (Sc203), approximately Sam thick, is sufficient for protection of environmental degradation of the MgCaO in environments of 100% humidity and elevated temperatures. This oxide/nitride interface is also able to withstand the processing temperatures of the nitride based HEMTs.