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Investigation of Si and O Donor Impurities in Unintentionally Doped MBE-Grown GaN on SiC(0001) Substrate

Tobias Tingberg (Institutionen för mikroteknologi och nanovetenskap, Fotonik) ; Tommy Ive (Institutionen för mikroteknologi och nanovetenskap, Fotonik) ; Anders Larsson (Institutionen för mikroteknologi och nanovetenskap, Fotonik)
Journal of Electronic Materials (0361-5235). Vol. 46 (2017), 8, p. 4898-4902.
[Artikel, refereegranskad vetenskaplig]

We have investigated the unintentional n-type background doping in GaN(0001) layers grown on semi-insulating 4H-SiC(0001) substrate by plasma-assisted molecular beam epitaxy under Ga-rich conditions at growth temperatures from 780A degrees C and 900A degrees C. All layers exhibited very smooth surface morphology with monolayer steps as revealed by atomic force microscopy. Hall-effect measurements showed that the sample grown at 900A degrees C had carrier concentration of 9.8 x 10(17) cm(-3) while the sample grown at 780A degrees C had resistivity too high to obtain reliable measurements. Secondary-ion mass spectroscopy revealed O and Si concentrations of < 10(17) cm(-3) in the sample grown at 900A degrees C but > 10(17) cm(-3) in the sample grown at 780A degrees C. The trend for the atomic concentrations of O and Si, which are common donor impurities in GaN, was thus contrary to the trend of the carrier concentration. The full-width at half-maximum for x-ray rocking curves obtained across the GaN(0002) and GaN(105) reflections for the sample grown at 900A degrees C was 62 arcsec and 587 arcsec, respectively. The half-width increased with decreasing growth temperature. The atomic concentrations of O and Si are too low to account for the unintentional background doping levels. A possible explanation proposed in early reports for the background doping is N-vacancies.

Nyckelord: Molecular beam epitaxy, gallium nitride, unintentional doping, Si donor, O donor, N-vacancy



Denna post skapades 2017-08-14.
CPL Pubid: 251078

 

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Institutioner (Chalmers)

Institutionen för mikroteknologi och nanovetenskap, Fotonik

Ämnesområden

Fotonik

Chalmers infrastruktur