Optical properties of AlGaN nanowires synthesized via ion beam techniques

Abstract

AlGaN plays a vital role in hetero-structure high electron mobility transistor by employing a two-dimensional electron gas and as electron blocking layer in the multi quantum well light emitting diodes. Nevertheless, the incorporation of Al in GaN for the formation of AlGaN alloy is limited by the diffusion barrier formed by instant nitridation of Al adatoms by reactive atomic N. Incorporation of Al above the miscibility limit, however can be achieved by ion beam technique. The well known ion beam mixing (IBM) technique was carried out with the help of Ar + irradiation for different fluences. A novel approach was also adopted for the synthesis of AlGaN by the process of post irradiation diffusion (PID) as a comparative study with the IBM technique. The optical investigations of AlGaN nanowires, synthesized via two different methods of ion beam processing are reported. The effect of irradiation fluence and post irradiation annealing temperature on the random alloy formation were studied by the vibrational and photoluminescence (PL) spectroscopic studies. Vibrational studies show one-mode phonon behavior corresponding to longitudinal optical (LO) mode of A1 symmetry (A1(LO)) for the wurtzite phase of AlGaN nanowires in the random alloy model. Maximum Al atomic percentage ~6.3-6.7% was calculated with the help of band bowing formalism from the Raman spectral analysis for samples synthesized in IBM and PID processes. PL studies show the extent of defects present in these samples. a)

Transfer-Free Graphene-Like Thin Films on GaN LED Epiwafers Grown by PECVD Using an Ultrathin Pt Catalyst for Transparent Electrode Applications

“…Thus, in this paper, a method of direct growth of GLTF on ultrathin platinum on GaN was demonstrated to avoid transfer. Unlike inert substrates such as SiO 2 , GaN is relatively prone to damage and requires subtle control over the growth process [29,30]. In our case, the growth temperature was reduced by the plasma enhancement technique, and the vertical cold wall system reduced the deposition time.…”

Effect of Oxygen and Aluminum Incorporation on the Local Structure of GaN Nanowires: Insight from Extended X-ray Absorption Fine Structure Analysis

“…Al atomic percentage (at.%) was calculated with the help of Raman spectroscopic analysis, which is indeed an indirect technique to calculate the alloy composition by exploiting Vegard's law. 30 Therefore, the actual information of the local structure and Al incorporation percentage is not clear from the previous study. In the present study, we intend to verify the Al incorporation at the Ga sites and other related information about the local structure by means of EXAFS analysis.…”

“…The detailed growth process is reported elsewhere. 30 In brief, in the IBM process, Al coated (~25 nm) as-grown GaN NW was irradiated with Ar + (25 keV) at fluences of 1E16 and 5E16 ions•cm -2 . In the PID process, prior to the coating of Al (~25 nm), the GaN NWs were irradiated with Ar + ion of the same energy and fluences as in the case of the IBM process.…”

Native defect-assisted enhanced response to CH4 near room temperature by Al0.07Ga0.93N nanowires

“…Post-irradiation annealing was carried out at a temperature of 1000 °C in N 2 (5N pure) atmosphere for 5 min as a final step for the formation of a random alloy, Al x Ga 1-x N. The detailed experiments were reported in our earlier study. 25 The fluence and post-irradiation parameters were chosen from optimum conditions obtained in the report.…”