Preparation of GaN thin film and Ga2O3 nanoribbons by plasma immersion ion implantation of N into GaAs

A method for producing gallium nitride (GaN) and gallium oxide (Ga2O3) nanoribbons by the combination of plasma immersion ion implantation of nitrogen into GaAs and rapid thermal annealing (RTA) has been investigated. Our approach uses a broad ion-impact energy distribution with variable implant doses to form a spread-out nitrogen depth profile and an amorphous surface layer. This approach circumvents the retained-dose limitation and low nitrogen content problems associated with ion beam implantation at fixed energy. Raman spectroscopy, transmission electron microscopy (TEM), x-ray diffraction and x-ray photoelectron spectroscopy were conducted on the samples. For the samples which had undergone RTA at 850 °C for 2 min, a Raman peak at 577 cm−1 associated with GaN was observed. The weak Raman intensity indicated that a small amount of GaN was present. Cross-sectional TEM imaging showed that the thickness of the region containing GaN was about 40 nm. When RTA was performed at 950 °C for 2 min, Ga2O3 nanoribbons were found on the GaAs sample surface instead. The ribbons were 0.1–2 μm in width, several tens of nanometers in thickness, and several tens of micrometers in length. Raman spectroscopy confirmed that the ribbons are single crystalline Ga2O3. In addition, the Ga2O3 ribbons were found to possess strong visible photoluminescence. The possible formation mechanism of these nanoribbons is discussed.