Tunable band gap of III-Nitride alloys obtained by Plasma Enhanced Atomic Layer Deposition

This work focuses on the obtention of ternary compounds of AlxGa1-xN and InxGa1-xN keeping constant the plasma exposition while varying the composition stoichiometry at temperatures ≤300 °C. The samples were fabricated by Plasma Enhanced Atomic Layer Deposition (PEALD) technique by alternating cycles of binary compounds, i.e. AlN or InN with GaN. Optical characterization was used to study the refractive index, energy band gap (Eg), and Urbach tales. Our findings indicate the ability to tune Eg selectively from deep ultraviolet to infrared region depending with the number of cycles of AlN or InN with GaN. For InxGa1-xN samples, Urbach energy values were associated with the random distribution of donor bound excitons being in the case of InGaN related to crystalline clusters within a specific stoichiometry. The variation of structural properties was evaluated by X-ray diffraction and X-ray reflectivity to identify the obtention of the crystallographic phase and the interfacial quality. Nevertheless, the analysis of depth distributions of Al, In, Ga, N has been profiled by the time of flight secondary ion mass spectrometry (ToF-SIMS).