Structure And Luminescence Of A-Plane Gan On R-Plane Sapphire Substrate Modified By Si Implantation*

We show the structural and optical properties of non-polar a-plane GaN epitaxial films modified by Si ion implantation. Upon gradually raising Si fluences from 5 x 10(13) cm(-2) to 5 x 10(15) cm(-2), the n-type dopant concentration gradually increases from 4.6 x 10(18) cm(-2) to 4.5 x 10(20) cm(-2), while the generated vacancy density accordingly raises from 3.7 x 10(13) cm(-2) to 3.8 x 10(15) cm(-2). Moreover, despite that the implantation enhances structural disorder, the epitaxial structure of the implanted region is still well preserved which is confirmed by Rutherford backscattering channeling spectrometry measurements. The monotonical uniaxial lattice expansion along the a direction (out-of-plane direction) is observed as a function of fluences till 1 x 10(15) cm(-2), which ceases at the overdose of 5 x 10(15) cm(-2) due to the partial amorphization in the surface region. Upon raising irradiation dose, a yellow emission in the as-grown sample is gradually quenched, probably due to the irradiation-induced generation of non-radiative recombination centers.