Epitaxial growth of GaN nanostructure by PA-MBE for UV detection application

We report the growth of lower aspect ratio, nano-island shaped, lower stress and strain facilitated gallium nitride nanostructures (GaN-NS) on Si (111) substrate via plasma assisted molecular beam epitaxy (PA-MBE) and fabrication of GaN-NS based UV photo-detection device even with NS's tiny dimensionality. GaN-NS were grown on Si (111) substrate with an inhomogeneous layer of Si3N4 which act as anti-surfactant to Ga atoms and also offer localized compressive strain. The developed strain can be relaxed by the growth of inhomogeneously oriented GaN-NS. The three dimension (3D) growth of GaN-NS in real time was observed by in-situ RHEED technique which displays transformation from streaky to spotty pattern. A micro-Raman technique has been employed to elaborate NS's crystallinity and lower stress value which is found be in good agreement with related lower strain as evaluated by HR-XRD spectra. A sharp near band edge emission at 363.2 nm is observed by room temperature photoluminescence measurement which signifies the presence of GaN. Metal semiconductor metal Au-GaN-NS/Si(111) device was fabricated to specifically analysed its ability to detect harmful ultraviolet radiations (325 nm) with GaN islands of just 26 nm height and 50 nm width. The performance of the fabricated device was analysed at fixed optical power of 13 mW with varying bias voltages (0.4-3 V).