Epitaxial Growth of GaN Nanowires with High Structural Perfection on a Metallic TiN Film

Wölz, Martin; Hauswald, Christian; Flissikowski, Timur; Gotschke, T.; Fernández-Garrido, Sergio; Brandt, O.; Grahn, H. T.; Geelhaar, Lutz; Riechert, H.

doi:10.1021/acs.nanolett.5b00251

Cited by 74 publications

(85 citation statements)

References 50 publications

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“…The substrate temperature was measured by a pyrometer, considering the emissivity of TiN (0.23 at this temperature) and absorption in the viewport. Reflection high‐energy electron diffraction (RHEED) revealed the pattern expected for cubic TiN, as observed by Wölz et al The growth of AlN was initiated by providing an Al flux of 1.7 × 10 14 atoms cm −2 s −1 (0.14 ML s −1 ) supplied by a conventional Knudsen cell, whereas the active N flux was not changed and corresponded to 1.03 × 10 15 atoms cm −2 s −1 (1.03 ML s −1 ). The N and Al atomic fluxes were calibrated by cross‐sectional imaging of thick GaN(0001) and AlN(0001) films, respectively, grown under slightly Ga‐ and N‐rich conditions on GaN/Al 2 O 3 (0001) substrates at 680 °C.…”

supporting

confidence: 53%

Self‐Assembly of Well‐Separated AlN Nanowires Directly on Sputtered Metallic TiN Films

Azadmand

Auzelle

Lähnemann

et al. 2020

Physica Rapid Research Ltrs

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Herein, the self‐assembled formation of AlN nanowires (NWs) by molecular beam epitaxy on sputtered TiN films on sapphire is demonstrated. This choice of substrate allows growth at an exceptionally high temperature of 1180 °C. In contrast to previous reports, the NWs are well separated and do not suffer from pronounced coalescence. This achievement is explained by sufficient Al adatom diffusion on the substrate and the NW sidewalls. The high crystalline quality of the NWs is evidenced by the observation of near‐band‐edge emission in the cathodoluminescence spectrum. The key factor for the low NW coalescence is the TiN film, which spectroscopic ellipsometry and Raman spectroscopy indicate to be stoichiometric. Its metallic nature will be beneficial for optoelectronic devices using these NWs as the basis for (Al,Ga)N/AlN heterostructures emitting in the deep ultraviolet spectral range.

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supporting

confidence: 53%

Self‐Assembly of Well‐Separated AlN Nanowires Directly on Sputtered Metallic TiN Films

Azadmand

Auzelle

Lähnemann

et al. 2020

Physica Rapid Research Ltrs

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“…Though direct growth of semiconductor nanowires on metals was demonstrated in several material systems, such as Si, Ge, CdS, and ZnO, it was only very recently reported by Wolz et al for GaN nanowires grown on sputtered Titanium (Ti) films . However, operating III‐Nitride nanowire devices electrically integrated and directly grown on metal were not yet demonstrated to our knowledge.…”

Section: Introductionmentioning

confidence: 90%

Semiconductor Nanowire Light‐Emitting Diodes Grown on Metal: A Direction Toward Large‐Scale Fabrication of Nanowire Devices

Sarwar

Carnevale

Yang

et al. 2015

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103

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Bottom-up nanowires are attractive for realizing semiconductor devices with extreme heterostructures because strain relaxation through the nanowire sidewalls allows the combination of highly lattice mismatched materials without creating dislocations. The resulting nanowires are used to fabricate light-emitting diodes (LEDs), lasers, solar cells, and sensors. However, expensive single crystalline substrates are commonly used as substrates for nanowire heterostructures as well as for epitaxial devices, which limits the manufacturability of nanowire devices. Here, nanowire LEDs directly grown and electrically integrated on metal are demonstrated. Optical and structural measurements reveal high-quality, vertically aligned GaN nanowires on molybdenum and titanium films. Transmission electron microscopy confirms the composition variation in the polarization-graded AlGaN nanowire LEDs. Blue to green electroluminescence is observed from InGaN quantum well active regions, while GaN active regions exhibit ultraviolet emission. These results demonstrate a pathway for large-scale fabrication of solid state lighting and optoelectronics on metal foils or sheets.

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“…16 It has been recently demonstrated that the NW growth on metal thin films helps to avoid such issues, hence reducing the potential barrier for carrier flow and allowing increased current injections with lower Joule heating. [17][18][19][20][21] As many efforts have been made in the UV III-nitride NW community to bring NW technology to a practical application, it is of particular importance to study the diode T j of such devices to evaluate the best configuration for efficient heat dissipation through the heat sink substrate, prevent overheating, short lifespan, and reduced light intensity. To date, there are no reports on UV AlGaN (and in general IIInitride) NWs LED T j measurements; therefore, this work consists of experimental findings that aim to enlighten the UV LED NW community for designing and optimizing the diode structures and substrate and to realize high power and reliable devices for eventual practical implementation.…”

Section: Introductionmentioning

confidence: 99%

Diode junction temperature in ultraviolet AlGaN quantum-disks-in-nanowires

Priante

ElAfandy

Prabaswara

et al. 2018

Journal of Applied Physics

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The diode junction temperature (Tj) of light emitting devices is a key parameter affecting the efficiency, output power, and reliability. Herein, we present experimental measurements of the Tj on ultraviolet (UV) AlGaN nanowire (NW) light emitting diodes (LEDs), grown on a thin metal-film and silicon substrate using the diode forward voltage and electroluminescence peak-shift methods. The forward-voltage vs temperature curves show temperature coefficient dVF/dT values of −6.3 mV/°C and −5.2 mV/°C, respectively. The significantly smaller Tj of ∼61 °C is measured for the sample on the metal substrate, as compared to that of the sample on silicon (∼105 °C), at 50 mA, which results from the better electrical-to-optical energy conversion and the absence of the thermally insulating SiNx at the NWs/silicon interface. In contrast to the reported higher Tj values for AlGaN planar LEDs exhibiting low lateral and vertical heat dissipation, we obtained a relatively lower Tj at similar values of injection current. Lower temperatures are also achieved using an Infrared camera, confirming that the Tj reaches higher values than the overall device temperature. Furthermore, the heat source density is simulated and compared to experimental data. This work provides insight into addressing the high junction temperature limitations in light-emitters, by using a highly conductive thin metal substrate, and it aims to realize UV AlGaN NWs for high power and reliable emitting devices.

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Epitaxial Growth of GaN Nanowires with High Structural Perfection on a Metallic TiN Film

Cited by 74 publications

References 50 publications

Self‐Assembly of Well‐Separated AlN Nanowires Directly on Sputtered Metallic TiN Films

Self‐Assembly of Well‐Separated AlN Nanowires Directly on Sputtered Metallic TiN Films

Semiconductor Nanowire Light‐Emitting Diodes Grown on Metal: A Direction Toward Large‐Scale Fabrication of Nanowire Devices

Diode junction temperature in ultraviolet AlGaN quantum-disks-in-nanowires

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