Abstract
AbstractFor certain growth conditions pronounced roughening has been observed for AlN layers grown on c‐plane sapphire by metal‐organic vapour phase epitaxy. TEM investigations revealed inversion domains correlated with the rough regions of the wafer. Al‐polar material was found at hillocks and N‐polar AlN in the valleys. We have investigated the early stages of growth and found three determining factors for the polarity development in AlN on c‐plane sapphire: substrate treatment by NH3 (nitridation) or TMAl preflow, substrate treatment by annealing under H2 atmosphere and the influence of parasitic depositions in the reactor. We propose a correlation between the sapphire surface termination and the polarity of AlN. Oxygen termination of sapphire is suggested to lead to N‐polarity and aluminium termination to Al‐polar AlN. By optimising the reactor condition, substrate treatment and growth conditions, smooth Al‐polar AlN layers were obtained for the subsequent growth of deep UV‐LED heterostructures. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
