Abstract
The growth of nitride on large-size and low-cost amorphous substrates has attracted considerable attention for applications in large-scale optoelectronic devices. In this paper, we reported the growth of GaN-based light-emitting diodes (LEDs) on amorphous SiO2 substrate with the use of nanorods and graphene buffer layers by metal organic chemical vapor deposition (MOCVD). The effect of different growth parameters on the morphology and vertical-to-lateral aspect ratio of nanorods was discussed by analyzing growth kinetics. Furthermore, we tuned nanorod coalescence to obtain continuous GaN films with a blue-LED structure by adjusting growth conditions. The GaN films exhibited a hexagonal wurtzite structure and aligned c-axis orientation demonstrated by X-ray diffractometer (XRD), Raman, and transmission electron microscopy (TEM) results. Finally, five-pair InGaN/GaN multi-quantum-wells (MQWs) were grown. The photoluminescence (PL) showed an intense emission peak at 475 nm, and the current–voltage (I-V) curve shows a rectifying behavior with a turn-on voltage of 5.7 V. This work provides a promising fabrication method for the large-area and low-cost GaN-based devices on amorphous substrates and opens up the further possibility of nitride integration with Si (100) complementary metal oxide semiconductor (CMOS) electronics.
Highlights
In recent years, GaN-based semiconductor materials have attracted considerable attention as significant building blocks for widespread applications on optoelectronic devices, such as light-emitting diodes (LEDs), laser diodes (LDs), as well as high-frequency and high-power transistors owing to their outstanding optical and electrical performance [1,2,3]
SiO2 (300 nm)/Si substrates with the graphene buffer layer, the pressure was varied from 120 Torr to
NH3 flow rate, and reactor temperature were set at 60 Torr, 90 sccm, and 1280 ◦ C, respectively, to obtain other hand, by studying the growth rule of nanocrystals under different conditions, we found that good nanorods morphology for further coalescence into the flat film
Summary
GaN-based semiconductor materials have attracted considerable attention as significant building blocks for widespread applications on optoelectronic devices, such as light-emitting diodes (LEDs), laser diodes (LDs), as well as high-frequency and high-power transistors owing to their outstanding optical and electrical performance [1,2,3]. Graphene acting as a buffer layer has attracted much interest in recent years, such as GaN-based LEDs prepared on graphene-covered sapphire [12,13,14], vertical-layout AlGaN nanorods obtained on graphene/silicon [15,16,17], and high-quality GaN or AlN films grown on graphene/SiC [18,19,20] These works are all based on single crystalline substrates. Due to the absence of dangling bonds, the pristine graphene surface causes high surface tension, leading to weak nucleation and cluster growth for the GaN buffer, which results in a high density of defects such as stacking faults and threading dislocations during the coalescence of nitrides [21,22] In this aspect, our group has previously proved the feasibility of AlGaN nanowire grown on the SiO2 /Si (100) substrate assisted with graphene [23]. We further grow GaN films with the use of AlGaN nanorods and graphene buffer layers on the amorphous substrate
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