Identification of Si and O donors in hydride-vapor-phase epitaxial GaN

Abstract

Donor impurity excitation spectra in the infrared from two high-quality, not-intentionally doped, hydride-vapor-phase epitaxial GaN wafers are reported. Two previously observed shallow donors which we designate N1 and N2 were observed in both wafers. However, spectra of one wafer are dominated by N1 and spectra of the other by N2. A comparison of infrared and secondary ion mass spectroscopic data allows identification of N1 as Si and N2 as O. Silicon is the shallowest uncompensated donor in these samples with an activation energy of 30.18±0.1 meV in the freestanding Samsung wafer. The activation energy of O is found to be 33.20±0.1 meV. An unidentified third donor with an activation energy of 31.23±0.1 meV also was observed. Integrated absorption cross sections are found to be 8.5×10−14 cm for Si and 8.6×10−14 cm for O.

Impurity breakdown and terahertz luminescence in n-GaN epilayers under external electric field

“…We attribute these two peaks to 1s-2p intracenter electron transitions for silicon and oxygen donors, respectively. Exactly at the same energies Moore et al 20 observed the optical absorption in n-GaN due to 1s-2p transitions for Si donors ͑at 23 meV͒ and for O donors ͑at 26 meV͒. The same two peaks dominate the THz electroluminescence spectrum.…”

Effect of high-temperature annealing on the residual strain and bending of freestanding GaN films grown by hydride vapor phase epitaxy

“…All the spectra from the Ga face surfaces are dominated by the sharp donor bound exciton ͑DBE͒ peaks, previously attributed to Si and O residual impurities in HVPE grown GaN material. 14 In addition, the A free exciton line X A in the higher energy side, an acceptor bound exciton line A 0 X in the lower energy side, as well as their phonon replicas are present in the PL spectra of both as-grown and annealed films. The narrow linewidths of the bound exciton related peaks down to 0.7 meV in all the films indicate high optical quality and nondestructive impact of the HTA treatment, although the surface roughness estimated by atomic force microscopy was found to increase from 0.5 nm in the as-grown sample up to 2.7 nm in the film annealed at 1450°C.…”

Time-resolved cathodoluminescence and photocurrent study of the yellow band in Si-doped GaN

“…Oxygen binding energies between 32 and 34 meV are usually reported in the literature. [29][30][31] On the contrary, there is a higher dispersion for Si energies reported by different authors. Some investigations reveal a binding energy of ͑29-31͒ meV in undoped samples, [29][30][31] while according to other experiments the position of the Si donor level in GaN:Si band gap lays 22 meV below the conduction band.…”

“…[29][30][31] On the contrary, there is a higher dispersion for Si energies reported by different authors. Some investigations reveal a binding energy of ͑29-31͒ meV in undoped samples, [29][30][31] while according to other experiments the position of the Si donor level in GaN:Si band gap lays 22 meV below the conduction band. 32,33 The existence of donors with binding energies lower than 25 meV-probably linked to intrinsic defects-has been also reported in GaN PL investigations.…”