Synthesis of Nanostructure InxGa1−xN Bulk Alloys and Thin Films for LED Devices

Abstract

In this study, we investigated an innovative method for the fabrication of nanostructure bulk alloys and thin films of indium gallium nitride (InxGa1-xN) as active, thin films for light-emitting diode (LED) devices using both crystal growth and thermal vacuum evaporation techniques, respectively. These methods resulted in some tangible improvements upon the usual techniques of InxGa1-xN systems. A cheap glass substrate was used for the fabrication of the LED devices instead of sapphire. Indium (In) and Gallium (Ga) metals, and ammonia (NH3) were the precursors for the alloy formation. The alloys were prepared at different growth temperatures with compositions ranging from 0.1≤x≤0.9. InxGa1-xN alloys at 0.1≤x≤0.9 had different crystallinities with respect to X-Ray diffraction (XRD) patterns where the energy bandgap that was measured by photoluminescence (PL) fell in the range between 1.3 and 2.5 eV. The bulk alloys were utilized to deposit the thin films onto the glass substrate using thermal vacuum evaporation (TVE). The XRD thin films that were prepared by TVE showed high crystallinity of cubic and hexagonal structures with high homogeneity. Using TVE, the InxGa1-xN phase separation of 0.1≤x≤0.9 was eliminated and highly detected by XRD and FESEM. Also, the Raman spectroscopy confirmed the structure that was detected by XRD. The FESEM showed a variance in the grain size of both alloys and thin films. The InxGa1-xN LED device with the structure of glass/GaN/n-In0.1Ga0.9N:n/In0.1Ga0.9N/p-In0.1Ga0.9N:Mg was checked by the light emitted by electroluminescence (EL). White light generation is a promising new direction for the fabrication of such devices based on InxGa1-xN LED devices with simple and low-cost techniques.

Pulsed Laser Deposition of In0.1Ga0.9N Nanoshapes by Nd:YAG Technique

“…The PL peak is observed in the yellow region. The deposited In0.1Ga0.9N (with energy bandgap of 2.08 eV) shows a red shift of the visible PL form the bulk target alloy (Eg = 2.65 eV) [9]. This shift may be related to application of the Nd:YAG technique.…”

“…Figure 3A shows the surface morphology of the In 0.1 Ga 0.9 N Bulk alloy (order distribution) [9] and deposited layer on glass substrate, with bright spots standing out against a darker background (disorder distribution). From our previous work [9], the bulk material had a nanowire structure with diameter of 69 nm and length of 341 nm. Moreover, the morphology of the film is not very dense, is free of cracks and has a relatively inhomogeneous distribution.…”

“…Additionally, the strain and relaxation may cause a mismatch between the deposited layer and substrate and have an effect on the energy gap of the deposited thin film [22]. Figure 3A shows the surface morphology of the In0.1Ga0.9N Bulk alloy (order distribution) [9] and deposited layer on glass substrate, with bright spots standing out against a darker background (disorder distribution). From our previous work [9], the bulk material had a nanowire structure with diameter of 69 nm and length of 341 nm.…”

“…Most of the In x Ga 1−x N targets used in PLD are fabricated by pressing the alloy powders at high pressure, followed by sintering at high temperatures [8]. From our previous work [9], In x Ga 1−x N bulk alloys have been prepared as a target by a simple novel method. III-nitride group has been deposited on sapphire (Al 2 O 3 ), silicon, Sic and GaN which play an important role in the stoichiometry of the thin film substrates [10].…”

Crystal Growth of Cubic and Hexagonal GaN Bulk Alloys and Their Thermal-Vacuum-Evaporated Nano-Thin Films

“…The ammonia flow rate is kept at 0.1 sccm. The tube temperature reaches 850 °C for 2 h in a muffle furnace (Carbolite AAF117) and then is reduced inside the furnace in order to prevent the segregations previously detected in InGaN alloys [ 16 , 17 ].…”