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

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 8.5x10(-14) cm for Si and 8.6x10(-14) cm for O. (C) 2001 American Institute of Physics.