A study on the silane doping of hetero-epitaxial MOCVD grown GaN

This paper presents a comprehensive study of SiH4 doping of GaN grown by me tal-organic chemical vapour deposition (MOCVD) on sapphire substrates. The silicon incorporation appeared to be virtually independent of the growth te mperature and a 1:1 relationship between the carrier concentration and the input mol fraction silane was found. Optical microscopy was used to study t he morphology of the layers where photoluminescence provided a measure of t he optical quality The electrical properties were determined with Hall meas urements and a comparison was made with ellipsometry measurements. The rela tionship between the free carrier concentration and the ellipsometric data made it possible to use ellipsometry as an alternative, quick, contactless and non-destructive technique to determine the free electron concentration in GaN layers doped with silicon.