Low temperature homoepitaxy of GaN by LP-MOVPE using Dimethylhydrazine and nitrogen

Abstract

Abstract Thin films of GaN with the V/III≈10 ratio were grown by low-pressure metal organic vapour phase epitaxy (LP-MOVPE) using N2 and Dimethylhydrazine (DMHy) as a carrier gas and nitrogen precursor, respectively. For the growth temperatures in the range from 550 to 690 ∘C the GaN layers exhibited good surface morphology. In the temperature range from approximately 550 to 610 ∘C, the growth rate increases with increasing temperature, characteristic of the process limited by surface kinetics with the activation energy of approximately 36 kcal/mol. For the temperatures between 620 and 690 ∘C, the growth rate was nearly independent of temperature, which is indicative of a mass transport limited growth. The activation energy was about 4.6 kcal/mol. Micro Raman spectroscopy revealed a significant relaxation of the selection rules for the scattering by the optical phonons in the films grown at lower temperatures. Variation of the intensity ratio for E 2 H and E 1 phonon modes has been attributed to the changes in the structural quality of the films grown at different temperatures.