Journal
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
Volume 135, Issue -, Pages -Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.mssp.2021.105903
Keywords
MOCVD; Residual GaN; System baking process; Dislocation density
Categories
Funding
- National Key R&D Program of China [2018YFB0406903]
- National Natural Science Foundation of China [62034008, 62074142, 62074140, 61974162, 61904172, 61874175]
- Beijing Nova Program [202093]
- Youth Innovation Promotion Association of Chinese Academy of Sciences [2019115]
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Residual GaN has been found to have a significant impact on two-step-grown GaN on sapphire substrates. A novel growth method involving TMGa and NH3 in the high-temperature surface treatment process has successfully improved the quality and stability of GaN epitaxial films on sapphire.
In this paper, it is found that the residual GaN has a great impact on the two-step-grown GaN on sapphire substrates. The samples which are grown with a conventional system baking process present a higher dislocation density than those without the baking process. It is found that, without baking, residual GaN accumulate in the MOCVD reactor, decompose, form the nucleation site on the sapphire substrate during the process of high-temperature surface treatment, and thus influence the initial nucleation process of GaN layer growth. Based on this understanding, a novel growth method to improve the quality and stability of two-stepgrown GaN on sapphire is proposed, in which the TMGa and NH3 were added in the high-temperature surface treatment process. With this method, as low as 3.71 x 107 cm-3 and 1.94 x 108 cm-3 for screw and edge dislocation density of GaN epitaxial films were achieved on sapphire.
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