SCM and SIMS investigations of unintentional doping in III-nitrides

Cross‐sectional scanning capacitance microscopy measurements of unintentionally doped model structures for InGaN quantum wells, GaN barriers and AlInN electron‐blocking layers showed n ‐type conductivity for the In‐containing layers. Secondary ion mass spectrometry indicated that oxygen impurities are the likely source of the electron density in the model layers. The n ‐type conductivity as well as the oxygen impurity level increases to ∼1018 cm‐3 for AlInN lattice‐matched to GaN. These results suggest that the background electron concentration due to oxygen impurities in indium‐containing layers needs to be considered in the design and theoretical modelling of device structures. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)