A Vapor Phase Self-Assembly of Porphyrin Monolayer as a Copper Diffusion Barrier for Back-End-of-Line CMOS Technologies

Naik, Tejas R.; Singh, Vibhas; Ravikanth, Mangalampalli; Rao, V. Ramgopal

doi:10.1109/ted.2016.2537370

Cited by 13 publications

(12 citation statements)

References 39 publications

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“…To measure the power of incident light, a calibrated silicon detector (Thor Laboratories, S130VC) and power meter (Thor Laboratories, PM-100D) were used. 17 To examine any changes in the surface roughness of bare and molecularly treated samples, AFM was used. AFM (Bruker, Dimension ICON) was used in tapping mode on different areas of the samples.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Surface Modification of AlN Using Organic Molecular Layer for Improved Deep UV Photodetector Performance

Kaushik

Naik

Alka

et al. 2020

ACS Appl. Electron. Mater.

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A direct wide bandgap of 6.2 eV, high temperature robustness, and radiation hardness make aluminum nitride (AlN) a preferable semiconductor for deep ultraviolet (UV) photodetection. However, the performance and reliability of AlN-based devices is adversely affected by a large density of surface states present in AlN. In this work, we have investigated the potential of a monolayer of organic molecules in passivating the surface states of AlN, which improved the performance of AlN-based metal− semiconductor−metal (MSM) deep UV photodetector. The organic molecules of the meso-5,10,15-triphenyl-20-(p-hydroxyphenyl)porphyrin Zn(II) complex (ZnTPP(OH)) were successfully adsorbed on an AlN surface, forming a self-assembled monolayer (SAM). The molecular layer was characterized by contact angle measurement, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The surface modification of AlN effectively reduced the dark current of the photodetector by 10 times without degrading the magnitude of photocurrent, especially at low voltages. The photo to dark current ratio (PDCR) was enhanced from 930 to 7835 at −2 V, and the responsivity doubled from 0.3 to 0.6 mA/W at 5 V. Moreover, the rise and fall times of the detector were found to decrease after the surface modification process. Our results suggest that SAM of porphyrin molecules effectively passivated the surface states in AlN, which resulted in improved photodetector performance.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Surface Modification of AlN Using Organic Molecular Layer for Improved Deep UV Photodetector Performance

Kaushik

Naik

Alka

et al. 2020

ACS Appl. Electron. Mater.

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“…1(b), the end group (−CH3) of the ZnTPP(OH) molecule is a hydrophobic group. 29 Therefore, the first test to examine the presence of SAM was the CA measurement. The CAs of bare, hydroxylated and SAM passivated Al0.5Ga0.5N films are shown in FIG.…”

Section: Characterization Of Sammentioning

confidence: 99%

“…A high CA of 98° was observed for SAM passivated film, which assured the presence of a hydrophobic layer on the Al0.5Ga0.5N surface. 29 31 Al−OH at 74.01 eV (FIG. 2 (e)), 27,34 HO−Ga at 530.66 eV, 31…”

Section: Characterization Of Sammentioning

confidence: 99%

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Organic passivation of Al_0.5Ga_0.5N epilayers using self-assembled monolayer of Zn(II) porphyrin for improved solar-blind photodetector performance

Kaushik¹,

Naik²,

Ravikanth³

et al. 2021

Semicond. Sci. Technol.

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We report on the passivation of surface states of Al0.5Ga0.5N epilayers by employing self-assembled monolayers (SAM) of organic molecules, which led to a significant improvement in the performance of Al0.5Ga0.5N based solar-blind photodetector. The formation of SAM of meso-(5-hydroxyphenyl)-10,15,20-tri(p-tolyl) porphyrin (ZnTPP(OH)) on the surface of Al0.5Ga0.5N was probed by contact angle measurement (CA), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The successful passivation of surface states was confirmed by Kelvin probe force microscopy (KPFM) as a significant decrease in the surface potential of Al0.5Ga0.5N by ~280 mV was observed. The inference was supported by a four-fold increase in the photoluminescence (PL) intensity of the near-band edge emission (NBE) peak upon passivation. As a result, the dark current of the as-fabricated solar-blind photodetector reduced by 2 orders of magnitude, without compromising with the magnitude of the photo current at 270 nm. The role of SAM was evident in improving the performance of the photodetector as the peak value of photo-to-dark current ratio (PDCR) enhanced by ~36 times. The peak responsivity of the photodetector increased from 1.6 to 2.2 mA/W at 10 V. The significant reduction in the dark current and enhancement in the responsivity led to an improvement in the specific detectivity by ~10 times. Additionally, the response speed of the photodetector was found to improve significantly from 4 to 0.5 s.

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“…The detailed molecular preparation is given elsewhere. 21 Zn-TPPOH molecular solute was then dissolved in toluene to form 10 À4 M molecular solution. The cleaned ohmic-contacted GaN samples were then placed in this molecular solution for 8 h (time decided after many optimizations) in air tight conditions to achieve the saturated surface coverage of the molecular monolayer on the sample surface.…”

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Significant improvement in the electrical characteristics of Schottky barrier diodes on molecularly modified Gallium Nitride surfaces

Garg

Naik

Pathak

et al. 2018

Applied Physics Letters

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III-Nitride semiconductors face the issue of localized surface states, which causes fermi level pinning and large leakage current at the metal semiconductor interface, thereby degrading the device performance. In this work, we have demonstrated the use of a Self-Assembled Monolayer (SAM) of organic molecules to improve the electrical characteristics of Schottky barrier diodes (SBDs) on n-type Gallium Nitride (n-GaN) epitaxial films. The electrical characteristics of diodes were improved by adsorption of SAM of hydroxyl-phenyl metallated porphyrin organic molecules (Zn-TPPOH) onto the surface of n-GaN. SAM-semiconductor bonding via native oxide on the n-GaN surface was confirmed using X-ray photoelectron spectroscopy measurements. Surface morphology and surface electronic properties were characterized using atomic force microscopy and Kelvin probe force microscopy. Current-voltage characteristics of different metal (Cu, Ni) SBDs on bare n-GaN were compared with those of Cu/Zn-TPPOH/n-GaN and Ni/Zn-TPPOH/n-GaN SBDs. It was found that due to the molecular monolayer, the surface potential of n-GaN was decreased by $350 mV. This caused an increase in the Schottky barrier height of Cu and Ni SBDs from 1.13 eV to 1.38 eV and 1.07 eV to 1.22 eV, respectively. In addition to this, the reverse bias leakage current was reduced by 3-4 orders of magnitude for both Cu and Ni SBDs. Such a significant improvement in the electrical performance of the diodes can be very useful for better device functioning.

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A Vapor Phase Self-Assembly of Porphyrin Monolayer as a Copper Diffusion Barrier for Back-End-of-Line CMOS Technologies

Cited by 13 publications

References 39 publications

Surface Modification of AlN Using Organic Molecular Layer for Improved Deep UV Photodetector Performance

Surface Modification of AlN Using Organic Molecular Layer for Improved Deep UV Photodetector Performance

Organic passivation of Al_0.5Ga_0.5N epilayers using self-assembled monolayer of Zn(II) porphyrin for improved solar-blind photodetector performance

Significant improvement in the electrical characteristics of Schottky barrier diodes on molecularly modified Gallium Nitride surfaces

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A Vapor Phase Self-Assembly of Porphyrin Monolayer as a Copper Diffusion Barrier for Back-End-of-Line CMOS Technologies

Cited by 13 publications

References 39 publications

Surface Modification of AlN Using Organic Molecular Layer for Improved Deep UV Photodetector Performance

Surface Modification of AlN Using Organic Molecular Layer for Improved Deep UV Photodetector Performance

Organic passivation of Al0.5Ga0.5N epilayers using self-assembled monolayer of Zn(II) porphyrin for improved solar-blind photodetector performance

Significant improvement in the electrical characteristics of Schottky barrier diodes on molecularly modified Gallium Nitride surfaces

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Organic passivation of Al_0.5Ga_0.5N epilayers using self-assembled monolayer of Zn(II) porphyrin for improved solar-blind photodetector performance