Identification of origin ofEC-0.6 eV electron trap level by correlation with iron concentration in n-type GaN grown on GaN freestanding substrate by metalorganic vapor phase epitaxy

The origin of E3 electron traps atE(C)-0.58 eV in GaN was investigated using Si-doped n-type GaN layers grown on freestanding GaN substrates using MOVPE. These layers contained impurity Fe at various concentrations depending on the growth conditions and the position within the wafer. Twenty E3 concentrations (N-T,N-E3) determined by deep-level transient spectroscopy were plotted against the corresponding Fe concentrations ([Fe]) obtained from secondary ion mass spectrometry. A correlation was evident betweenN(T,E3)and [Fe] in the range (0.4-12) x 10(15) cm(-3), suggesting that the E3 level in MOVPE-grown homoepitaxial GaN originates from the substitution of Fe atoms at Ga sites.