The growth characteristics of Fe-doped GaN epitaxial layers on semi-insulating SiC (001) substrates were studied using metalorganic chemical vapor deposition for high breakdown voltage device applications. A smooth Fe-doped GaN epilayer surface can be realized by changing the ferrocene flow, while higher Fe concentrations in the GaN epilayer affect the surface morphology. To reduce the Fe trapping carrier and the sheet resistances of the two-dimension electron gas generated from the interface of AlGaN and GaN, the thickness ratio of Fe-doped and undoped GaN bi-epilayers was also optimized. AlGaN/GaN high electron mobility transistors with the optimum doping concentration of Fe-doped GaN and suitable thickness of undoped GaN have been successfully developed. The achieved breakdown voltage of the Fe-doped GaN epitaxial layer can be as high as 2457 V, which is attributed to the Fe-doped GaN epitaxial layer with higher resistance, which can sustain the high breakdown voltage. The details of the correlation between the surface morphology, Fe concentration, and thickness of Fe-doped GaN epitaxial layers used for high breakdown voltage devices will be also discussed in this paper.
- Fe-doped GaN
- Metalorganic chemical vapor deposition
- Semi-insulating SiC
- Surface morphology
- Two-dimension electron gas