| Summary: | 博士 === 國立清華大學 === 電子工程研究所 === 103 === In this study, the Gallium Nitride (GaN) p-i-n diodes grown on pattern sapphire substrates by MOCVD have been fabricated to study the electrical characteristics of the GaN p-i-n diodes. To be a great high power device, the reverse breakdown characteristics of GaN p-i-n diodes are dominated by the capabilities of defect suppression at reverse bias; at the same time, the forward series resistances of GaN p-i-n diodes must be reduced for low power dissipation at forward bias.
In this study, firstly, the edge termination effects of the GaN p-i-n diodes including the damages resulted from ICP etching and electric field distribution were inhibited by using two-step mesa structure and suitable process parameters, and these fabricated devices exhibited great performances. After the suitable process flow has been confirmed, the GaN p-i-n diodes with ultra-low i- layer concentration have been fabricated.
Finally, the results of the devices with ultra-low i- layer concentration and two-step mesa structures show the high BFOM values and the high breakdown voltage values, respectively. The device with the highest BFOM is very close to the dash line for SiC-limit. The fabricated devices with suitable process parameters and low i- layer concentrations are greater than the previous reports of the GaN p-i-n diodes grown on sapphire substrates.
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