Optical characterization of GaN doping superlattices: as grown, hydrogen implanted, and annealed

Abstract

Hydrogen–ion implantation was studied for GaN doping superlattices. The samples were grown epitaxially with eight periods of n-GaN/p-GaN (50 nm/50 nm) doped with 1018 cm−3 (n-Si) and 1018 cm−3 (p-Mg), and with a thin Aluminium Nitride layer (AIN) nucleation layer (20 nm) on a (0001) sapphire substrate. Low temperature photoluminescence and Raman spectroscopy were used to characterize the as grown and hydrogen implanted (dose 1012−1017 cm−2, energy 1 MeV) samples. In the studied (relatively narrow) region of the laser power, the as grown samples show neither tunable effective band gap nor the subband structure. Implantation induces the yellow band (YL) which is not present in the spectra of as grown samples. The peak position of the YL band shifts towards higher energy with increasing implantation dose. Raman spectroscopy reveals implantation induced broad band centred at 1618 cm−1, with many shoulders and several sharp peaks in the region of 2127−1411 cm−1. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)