Facile Formation of High-Quality InGaN/GaN Quantum-Disks-in-Nanowires on Bulk-Metal Substrates for High-Power Light-Emitters

Abstract

High-quality nitride materials grown on scalable and low-cost metallic substrates are considerably attractive for high-power light-emitters. We demonstrate here, for the first time, the high-power red (705 nm) InGaN/GaN quantum-disks (Qdisks)-in-nanowire light-emitting diodes (LEDs) self-assembled directly on metal-substrates. The LEDs exhibited a low turn-on voltage of ∼2 V without efficiency droop up to injection current of 500 mA (1.6 kA/cm(2)) at ∼5 V. This is achieved through the direct growth and optimization of high-quality nanowires on titanium (Ti) coated bulk polycrystalline-molybdenum (Mo) substrates. We performed extensive studies on the growth mechanisms, obtained high-crystal-quality nanowires, and confirmed the epitaxial relationship between the cubic titanium nitride (TiN) transition layer and the hexagonal nanowires. The growth of nanowires on all-metal stack of TiN/Ti/Mo enables simultaneous implementation of n-metal contact, reflector, and heat sink, which greatly simplifies the fabrication process of high-power light-emitters. Our work ushers in a practical platform for high-power nanowires light-emitters, providing versatile solutions for multiple cross-disciplinary applications that are greatly enhanced by leveraging on the chemical stability of nitride materials, large specific surface of nanowires, chemical lift-off ready layer structures, and reusable Mo substrates.

Determination of band offsets at GaN/single-layer MoS2 heterojunction

“…[1][2][3][4] These unavoidable defects in GaN mainly stem from its large lattice mismatch with the most commonly used foreign substrates Sapphire, SiC, and Si. 5,6 On the other hand, transition metal dichalcogenides (TMDs) are emerging as a novel material system exhibiting good electronic and optoelectronic properties in recent years.…”

Recent Advances on p-Type III-Nitride Nanowires by Molecular Beam Epitaxy

“…Moreover, their optical qualities seem to be not compromised, e.g., InN and GaN nanowires grown on silicon oxide show similar photoluminescence characteristics compared to the nanowires grown on Si [99]. Recently, visible and UV LEDs with InGaN and AlGaN quantum wells/quantum disks have been demonstrated on metal substrates [102][103][104][105][106]. III-nitride nanowire structures on graphene have also been investigated.…”

Thermodynamic photoinduced disorder in AlGaN nanowires

“…The nanowires were grown using plasma-assisted MBE. 35,40 The nanowires consisted of 10 nm unintentionally-doped GaN nanobuffers and approximately 290 nm unintentionally doped AlGaN layers grown sequentially. Before the growth of AlGaN, thin GaN nanowire array template was grown to promote the formation of AlGaN nanowires.…”

“…29 GaN-based nanowires have recently emerged as the center of attention as potential building blocks for future nanostructured long-term stable opto-electrothermal devices. [30][31][32] Even though GaN nanowire-based devices, including tunnel-injected DUV light-emitting diodes (LEDs) 33 and LEDs for monolithic metal-optoelectronics 34 and high-power light emitters, 35 have recently been realized, understanding and optimizing the electrothermal characteristics 36,37 of GaN-based nanowires is critical for identifying and achieving their full potential in opto-electrothermal device applications. 38,39 As a consequence of the thermal activation of non-radiative recombination channels, we observed an increasing trend in the amount of generated photoinduced entropy of the InGaN nanowire system as its temperature approached room temperature, which is a valid assessment of the thermodynamic disorder in photoluminescent semiconducting materials.…”