Search for: All records

Abstract An extensive examination of the nanoscale, crystallographic growth dynamics of the system, which is impacted by the thermal energy given to the GaN, is carried out to derive a deeper understanding of the growth kinetics, morphology and microstructure evolution, chemical bonding, and optical properties of Ga─O─N films. Thermal annealing of GaN films is performed in the temperature range of 900–1200 °C. Crystal structure, phase formation, chemical composition, surface morphology, and microstructure evolution of Ga─O─N films are investigated as a function of temperature. Increasing temperature induces surface oxidation, which results in the formation of stable β‐Ga₂O₃phase in the GaN matrix, where the overall film composition evolves from nitride (GaN) to oxynitride (Ga─O─N). While GaN surfaces are smooth, planar, and featureless, oxidation induced granular‐to‐rod shaped morphology evolution is seen with increasing temperature to 1200 °C. The considerable texturing and stability of the nanocrystalline Ga─O─N on Si substrates can be attributed to the surface and interface driven modification because of thermal treatment. Corroborating with structure and chemical changes, Raman spectroscopic analyses also indicate that the chemical bonding evolution progresses from fully Ga─N bonds to Ga─O─N. While the GaN oxidation process starts with the formation of β‐Ga₂O₃at an annealing temperature of 1000 °C, higher annealing temperatures induce structural distortion with the potential formation of Ga─O─N bonds. The structure‐phase‐chemical composition correlation, which will be useful for nanocrystalline materials for selective optoelectronic applications, is established in Ga─O─N films made by thermal treatment of GaN. 

Abstract With the astonishing advancement of present technology and increasing energy consumption, there is an ever‐increasing demand for energy‐efficient multifunctional sensors or transducers based on low‐cost, eco‐friendly material systems. In this context, self‐assembled vertically alignedβ‐Ga_2−xW_xO₃nanocomposite (GWO‐VAN) architecture‐assisted self‐biased solar‐blind UV photodetection on a silicon platform, which is the heart of traditional electronics is presented. Utilizing precisely controlled growth parameters, the formation of W‐enriched verticalβ‐Ga_2−xW_xO₃nanocolumns embedded into the W‐deficientβ‐Ga_2−xW_xO₃matrix is reached. Detailed structural and morphological analyses evidently confirm the presence ofβ‐Ga_2−xW_xO₃nanocomposite with a high structural and chemical quality. Furthermore, absorption and photoluminescence spectroscopy explains photo‐absorption dynamics and the recombination through possible donor–acceptor energy states. The proposed GWO‐VAN framework facilitates evenly dispersed nanoregions with asymmetric donor energy state distribution and thus forms build‐in potential at the verticalβ‐Ga_2−xW_xO₃interfaces. As a result, the overall heterostructure evinces photovoltaic nature under the UV irradiation. A responsivity of ≈30 A/W is observed with an ultrafast response time (≈350 µs) under transient triggering conditions. Corresponding detectivity and external quantum efficiency are 7.9 × 10¹²Jones and 1.4 × 10⁴%, respectively. It is believed that, while this is the first report exploiting GWO‐VAN architecture to manifest self‐biased solar‐blind UV photodetection, the implication of the approach is enormous in designing electronics for extreme environment functionality and has immense potential to demonstrate drastic improvement in low‐cost UV photodetector technology.