Sol–Gel Spin Coating Growth of Magnesium-Doped Indium Nitride Thin Films on Different Substrates

Abstract

We report on the growth of p-type indium nitride (InN) thin films on different substrates using a relatively simple and cost-effective sol-gel spin coating method. The precursors for the indium source and p-type dopant were indium nitrate hydrate and magnesium chloride 6-hydrate powders, respectively. The structural, morphology, and optical properties of p-type InN thin films grown on different substrates were investigated. X-ray diffraction patterns revealed that the deposited Mg-doped InN thin film on GaN/AlN/Si(111) template show polycrystalline wurtzite structure with a strong InN(002) orientation and have a good crystallinity. Field emission scanning electron microscopy images and energy dispersive X-ray results showed that all the films exhibit densely packed surface morphology with hexagonal-like grains shape and low oxygen percentage with almost 1:1 ratio of indium to nitrogen. Moreover, two Raman-active modes of E₂(High) and A₁(LO) of the wurtzite InN were clearly observed for all samples. The ultraviolet-visible-near infrared spectroscopy results showed that the energy bandgap of the Mg-doped InN thin films was in the range of 1.62-1.66 eV. From all the results, it can be concluded that the Mg doped InN film on GaN/AlN/Si(111) substrate has better crystalline quality as compared to that of other substrates.