The growth of unintentionally doped GaN films was performed by organometallic vapor phase epitaxy on (0001) sapphire substrates using a home-made vertical reactor at atmospheric pressure.These GaN films were grown using trimethylgallium(TMGa) and triethylgallium(TEGa) as Ga precursors under different growth condition.The blue-ammonia was used as N source.The mixed gases of hydrogen and nitrogen were used as the carrier gases.The sapphire substrate was heated at 1100℃ for 10 minutes before the GaN growth.Then a thin buffer layer with thickness of about 15nm was grown at 520℃ and recrystallized at 1060℃ for 6 minutes.The GaN films were grown at 1060℃ and its thickness was about 1μm.The morphorlogical

crystalline

electrical and optical characteristics of GaN films were measured by metalloscope observation

X-ray double crystal diffraction measurement

Van der Pauw Hall method and PL spectra measurement at room temperature

respectively.The metalloscope observation results indicated that the epilayer of sample A was uncontinuous.So we inferred that the nucleation sites were not enough when using TEGa as buffer’s Ga source.By analyzing the experiment results and growth condition

it is suggested that TEGa is not very suitable to be used as buffer layer’s Ga precursor

but it is good precursor as the epilayer’s sources in growth of GaN films.The carrier gas ratio[H

2

]/[N

2

]influenced the epilayer quality greatly.When using TEGa as epilayer’s Ga source and TMGa as buffer’s Ga source

we obtained GaN single crystal films with RT background carrier concentration of 4.5×10

17

cm

-3

and the mobility of 198cm

2

/V·s.The PL measurement indicated that the blue luminescence can be suppressed using TEGa as the epilayer’s Ga precursor.