p-Type Modulation Doped InGaN/GaN Dot-in-a-Wire White-Light-Emitting Diodes Monolithically Grown on Si(111)

Abstract

Full-color, catalyst-free InGaN/GaN dot-in-a-wire light-emitting diodes (LEDs) were monolithically grown on Si(111) by molecular beam epitaxy, with the emission characteristics controlled by the dot properties in a single epitaxial growth step. With the use of p-type modulation doping in the dot-in-a-wire heterostructures, we have demonstrated the most efficient phosphor-free white LEDs ever reported, which exhibit an internal quantum efficiency of ∼56.8%, nearly unaltered CIE chromaticity coordinates with increasing injection current, and virtually zero efficiency droop at current densities up to ∼640 A/cm(2). The remarkable performance is attributed to the superior three-dimensional carrier confinement provided by the electronically coupled dot-in-a-wire heterostructures, the nearly defect- and strain-free GaN nanowires, and the significantly enhanced hole transport due to the p-type modulation doping.

Photoelectrochemical reduction of carbon dioxide using Ge doped GaN nanowire photoanodes

“…The growth conditions included a substrate temperature of 750 • C, nitrogen flow rate of 1.0 sccm, plasma forward power of 350 W, and Ga beam equivalent pressure of ∼6 × 10 −8 Torr. 13,36,37 The Ge effusion cell temperature was 1130 • C, which corresponds to Ge beam equivalent pressure (BEP) of ∼10 −11 Torr, which is similar the previous reports. 35,38 Due to the suitable atom size, Ge can be incorporated into GaN with less lattice distortion and can provide better nanowire morphology, compared to Si-doping.…”

Group III-nitride nanowire structures for photocatalytic hydrogen evolution under visible light irradiation

“…InGaN nanowire arrays were grown on top of a GaN nanowire template to achieve superior structural and optical properties. 35 As shown in the schematic of Fig. 2(a), several segments of InGaN ternary nanowires capped with a thin GaN layer were incorporated in order to minimize the formation of misfit dislocations.…”

Design analysis of phosphor-free monolithic white light-emitting-diodes with InGaN/ InGaN multiple quantum wells on ternary InGaN substrates

“…[6][7][8][9][10] The chromaticity coordinates and correlated color temperature (CCT) of the proposed white LEDs on ternary substrates also demonstrated comparable results with those nanostructured white LEDs. 14,15 Note that the strain in InGaN/ InGaN QW on ternary InGaN substrate can be reduced by up to ∼75% compared to conventional InGaN/ GaN QW on GaN substrate as pointed out by previous work. 23 The significantly decreased strain resulted in substantial reduction of piezoelectric polarization fields and internal electrostatic fields in the QWs, and consequently led to suppression of the charge separation effect.…”

“…[6][7][8][9][10][11][12][13][14][15][16][17][18][19] Previous works have reported the possibility of fabricating phosphor-free monolithic white LED by stacking multi-color-emitting InGaN/ GaN quantum wells (QWs) on GaN substrate. [6][7][8][9][10] However, it is very challenging to incorporate high In-content into InGaN/ GaN QWs on GaN substrate which is critical for green and yellow emission wavelengths due to charge separation issue from large lattice-mismatch strain.…”

“…1,5 The CCT values from LEDs (A) and (B) are also comparable with those of nanostructure white LEDs (∼ 4500 -6500 K). 14,15 For comparison purpose, . These results suggest that our proposed monolithic white InGaN/ InGaN MQW LED structures can achieve stable white color illumination and promising efficiency, while only require standard device fabrication processes.…”