Strain engineering during MOVPE growth of GaN on Si(111)

Growth of thick, crack-free GaN layers on Si is difficult due to the high thermal mismatch of these materials. To obtain stress reduction compressive stress can be applied during growth using AlN/GaN superlattices [1] or low-temperature (LT) AlN interlayers [2]. We present in- and ex-situ stress measurements of crack-free GaN layers in excess of 5 µm grown using LT-AlN interlayers. For in-situ measurements we use a multibeam stress-sensor. Ex situ characterisation was performed by highly resolved x-ray diffraction, cathodoluminescence, raman measurements and by transmission electron microscopy. We also discuss the strong influence of doping and in-situ deposited SiN masks on stress evolution during growth.