Investigation of Si and O Donor Impurities in Unintentionally Doped MBE-Grown GaN on SiC(0001) Substrate
Artikel i vetenskaplig tidskrift, 2017

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.

Si donor

Molecular beam epitaxy

unintentional doping

gallium nitride

N-vacancy

O donor

Författare

Tobias Tingberg

Chalmers, Mikroteknologi och nanovetenskap (MC2), Fotonik

Tommy Ive

Chalmers, Mikroteknologi och nanovetenskap (MC2), Fotonik

Anders Larsson

Chalmers, Mikroteknologi och nanovetenskap (MC2), Fotonik

Journal of Electronic Materials

0361-5235 (ISSN)

Vol. 46 4898-4902

Ämneskategorier

Telekommunikation

DOI

10.1007/s11664-017-5484-y