Rectification and barrier height inhomogeneous in Rhodamine B based organic Schottky diode

doi:10.1016/j.synthmet.2010.10.030

Synthetic Metals

Volume 161, Issues 1–2, January 2011, Pages 32-39

https://doi.org/10.1016/j.synthmet.2010.10.030 Get rights and content

Abstract

Thermogravimetric analysis (TGA) and X-ray diffraction (XRD) were used to study the structure characterization of the Rhodamine B (Rh.B). The thermal stability and the lattice parameters were calculated using TGA and XRD, respectively. Bulk Al/Rh.B Schottky barrier device was prepared and their properties have been investigated by current density–voltage J–V and capacitance–voltage C–V characteristics in the temperature range 300–400 K. The device parameters extracted from the J–V and C–V characteristics are strongly influenced by the effect of temperature. The device exhibits a strong rectification characteristic and shows a maximum rectification ratio at ≈0.15 V for all the studied temperature range. The results clearly demonstrate that the electron transport at the Al/Rh.B interface is significantly affected by low barrier patches. The discrepancy between Schottky barrier heights (SBHs) obtained from the temperature dependencies of both J–V and C–V measurements is explained by the introduction of a spatial distribution of BHs due to the barrier height inhomogeneities that prevail at the Al/Rh.B interface. The deviations of apparent BHs were investigated by considering the microstructure of the Al/Rh.B interface. Moreover, the distribution of carrier concentration through the width of the depletion region is nearly uniform.

Introduction

Rhodamine dyes family was among the oldest and most commonly used of all synthetic dyes and used in the field of different areas. Initially, they were used for cloth coloration [1], [2], [3]. Owing to their unique optical properties, they served as water tracing agents, fluorescent markers for microscopic structure studies, photosensitizers, and as laser dyes. The rhodamine B itself is a commercially available dye with high purity and stability [2], [3], [4], [5], [6], [7].

In recent years, there are many research works focusing on the fabrication of electrical devices based on rhodamine family. Karataş et al. [7] have reported that the non-polymeric organic compound known as Rhodamine 110 (Rh.101) interfaced to the inorganic p-Si provides the rectifying I–V characteristics. They have obtained a value of 0.817 eV for the Al/Rh.101/p-Si/Al contact at the room temperature that is significantly larger than the value of 0.58 eV of the conventional Al/p-Si Schottky diode. Furthermore, they have fitted the results to a model of a Gaussian distribution of the barrier heights to explain the fluctuations of the characteristic parameters suggesting that the contacts are not spatially uniform. Ahmed and yassin [8] have fabricated poly[2-methyl-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) conducting polymers Schottky diodes and investigated the effect of doping MEH-PPV conjugate polymer by Nile blue (NB) and Rhodamine B (Rh.B) as electron acceptor fluorescent dyes on their current–voltage characteristics. They have found that the dielectric permittivity of the active layer of the organic layer is an important factor in determining the efficiency of the MEH-PPV Schottky diode. Vural et al. [9] have showed that the rectifying contacts of electronic devices can be fabricated using an organic compound layer such as Rh.101 between metal and inorganic semiconductor such as GaAs. They have reported that the diode parameters values are remarkably different from those given for metal/GaAs semiconductor contacts in literature. Karataş and Çakar [10] have studied the electrical properties of Sn/Rh.101/p-Si/Al Schottky structures. They found that the interface state densities have an exponential rise with bias from 0.16 E_V to 0.92 E_V, for the mid-gap towards the top of the valence band of the p-Si. They concluded that Rh.101 organic layer controls electrical charge transport properties of Sn/p-Si Schottky structure, and it has been shown that the rectifying contacts or electronic devices can be fabricated using an organic compound layer between metal and inorganic semiconductor. Recently, the conduction mechanism of Rhodamine B was studied under the effect of dc and ac fields by Yahia and co-workers [11]. They concluded that Rhodamine B has a semiconducting characteristics and the ac conduction mechanism is controlled by correlated barrier hopping, CBH model.

According to the aforementioned survey, the purpose of the present study is to examine whether or not the Al/Rh.B contact, without using any single crystalline substrate, can be used as a rectifying contact and obtained a higher barrier height than that of using conventional inorganic Schottky contact at room temperature. Furthermore, the temperature dependence of the experimental forward bias current density–voltage (J–V) and capacitance–voltage (C–V) characteristics for the prepared device were investigated over the temperature range of 300–400 K.

Section snippets

Materials

Rhodamine B, [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene] diethylammonium chloride, was obtained from Aldrich with high purity. Pure aluminum and gold were used as rectifying and ohmic contacts with Rh.B, respectively.

Processes and fabrication of the Al/Rh.B device

Discs of 1 mm thickness and 6.5 mm radius of the Rh.B dye were formed via the application of 5 tons. The ohmic (Au) and non-ohmic (Al) electrodes were evaporated on the Rh.B discs using a high vacuum coating unit (Edwards, E-306 A), kept at room temperature during the

Thermogravimetry analysis and X-ray diffraction of Rh.B

Thermogravimetry analysis (TGA) is a process in which a substance is undergoes to decompose in the presence of heat, which causes bonds within the molecules to be broken. TGA plays an important role in determining the thermal stability of different materials especially for organic substances. TGA thermogram of Rh.B is shown in Fig. 2. As observed, Rh.B is stable in the temperature up to 210 °C. After which the weight loss is occurred in an individual step whereas the loss occurred during the

Conclusion

TGA analysis illustrates that Rh.B has a high stability up to 210 °C. The analysis of XRD for Rh.B in powder form revealed the polycrystalline nature of tetragonal structure with space group P4. Temperature dependence of J–V and the reverse bias C–V characteristics of Al/Rh.B structure were investigated. It was seen that a high rectification characteristics are observed. Moreover, there is a discrepancy between barrier heights obtained from J–V and C–V measurements. This discrepancy is

References (36)

Q. Meng et al.
Dyes Pigments
(2007)
Ş. Karataş et al.
Appl. Surf. Sci.
(2006)
F.E. Ahmed et al.
Microelectron. J.
(2007)
Ö. Vural et al.
Synth. Met.
(2007)
Ş. Karataş et al.
Synth. Met.
(2009)
Sh.A. Mansour et al.
Dyes Pigments
(2010)
M.M. El-Nahass et al.
Appl. Surf. Sci.
(2008)
M. Sahin et al.
Appl. Surf. Sci.
(2005)
A.A.M. Farag
Appl. Surf. Sci.
(2009)
Ş. Karataş et al.
Physica B
(2007)

A.A.M. Farag et al.

J. Alloys Compd.

(2010)

Y.S. Ocak et al.

Synth. Met.

(2009)

Ö. Güllü et al.

Microelectron. Eng.

(2008)

A.A.M. Farag et al.

J. Alloys Compd.

(2009)

S. Aydogan et al.

Polymers

(2005)

A.F. Ozdemir et al.

Thin Solid Films

(2003)

A.A.M. Farag et al.

Int. J. Hydrogen Energy

(2009)

H. Korkut et al.

Microelectron. Eng.

(2009)

Cited by (108)

Synthesis and investigation of linear and nonlinear optical properties of an octahedral metalloporphyrin
2024, Optical Materials
Metalloporphyrins are the natural light harvesting antennas and are extensively used as sensing and optoelectronic materials. Herein, we are reporting the synthesis and investigation of the optical properties of a novel octahedral metalloporphyrin, SnPMX. The structure of SnPMX is established by the IR, UV–visible, ¹H NMR, and HRMS techniques. Thermal evaporation is used to grow thin films of SnPMX on quartz surfaces. The surface morphology and structural parameters of the as deposited thin films are investigated by the use of powder XRD and SEM. The linear and nonlinear optical parameters of the SnPMX are investigated by employing the Wemple-DiDomenico and Drude single oscillator models. The SnPMX presented a higher value of the lattice dielectric ( $ε_{L} =$ 5.79) than the high frequency dielectric ( $ε_{\infty}$ = 4.76) which confirmed the presence of free carriers and lattice vibrations. The short relaxation time (τ = 2.30 × 10⁻²⁰ s), higher optical mobility ( $μ_{o p t .}$ = 9.19 × 10⁻⁹ C. Sec/Kg) and third order nonlinear susceptibility ( $χ^{3}$ = 1.37 × 10⁻¹² esu) support its potential use in optoelectronics and photonics. In the absorbing region, SnPMX presented 2.67 eV of direct optical band gap energy, and in the non-absorbing region, two distinct Urbach energies of 1.01 and 1.90 eV were observed, which indicate the electron-phonon or exciton-phonon interactions. These results indicate that SnPMX can be used for NLO and optical limiting applications.
Doped sol-gel based microstructured layers to improve the light emission of luminescent coatings
2023, Journal of Alloys and Compounds
Sol-gel based layers doped with Rhodamine B phosphors (RB) were directly microstructured to produce sub-lambda 2D gratings, using nanoimprint lithography. Such an approach enables the simplification of technological processes, since no further etching process is required, which reduces considerably the number of technological steps and thus production costs. Surface microstructuring improved fluorophore emission in the visible range. Demonstrations were performed experimentally and samples were characterized using angle-resolved fluorescence. The emissions measured on microstructured luminescent coatings were 3–4 times higher, depending on the angle of observation, than those recorded on flat surfaces. This technological approach is very promising for the next generation of low-cost, high-performance anti-counterfeiting marking processes and for the traceability of objects based on unique optical effects.
Structural and electronic characterization of silicon based MIS contact by xanthene dye molecules (Erythrosine B)
2023, Surfaces and Interfaces
The effect of erythrosine B (ERY) organic material as an interface layer on the electronic characteristics of the Al/p-Si junction is examined in the present work. AFM, NMR, UV–Vis and FTIR measurements have been conducted on the ERY dye molecule. The ERY film on the surface of the substrate is coated with nanoparticles, according to the surface analysis performed using the AFM technique. The basic diode parameters of Al/p-Si and Al/ERY/p-Si junctions were measured by utilizing current-voltage (I–V) and capacitance-voltage (C-V) techniques. The junctions with and without organic interfacial layers were found to have ideality factors of 1.931 and 1.925, respectively. For MS and MIS contacts, the estimated values of barrier height were 0.592 eV and 0.937 eV, respectively. Additionally, the series resistances for the MS and MIS structures by utilizing Norde function, were determined to be 0.14 kΩ and 322.85 kΩ, respectively. In addition, the reverse bias 1/C²-V characteristics were used to analyze the barrier height values and compare the findings to those from I-V method. The experimental findings demonstrated that the Al/ERY/p-Si MIS diode has a barrier height that is remarkably greater than that of the reference Al/p-Si junction. Placement of the ERY dye interlayer between a metal and a semiconductor could enhance and regulate the performance and characteristic of these types of junctions.
Carmoisine azo dye-modified Al/p-Si junction
2023, Materials Chemistry and Physics
This study investigates the impact of a Carmoisine azo dye layer on electronic transport at the p-silicon/Al interface. The morphology of the Carmoisine azo layer is characterized using atomic force microscopy (AFM). Various spectroscopic measurements, including nuclear magnetic resonance (NMR), ultraviolet–visible (UV–Vis), and Fourier transform infrared (FTIR) spectroscopy, are employed to analyze the Carmoisine dye molecule. The direct and indirect band gap values of the Carmoisine dye molecule, prepared in methanol solvent, are determined to be E_g,1 = 2.15 eV and 2.06 eV (D band) and E_g,2 = 3.54 eV and 3.35 eV (C band), respectively. Results indicate that the Carmoisine film on a glass slide consists of non-homogeneous microstructures, with a surface roughness of 16.76 nm. A spin coater is used to form an Al/Carmoisine/p-Si device, which is a cost-effective and readily scalable approach for creating semiconductor films. The basic contact parameters of the Al/p-Si and Al/Carmoisine/p-Si contacts are measured using current-voltage (IV) and capacitance-voltage (CV) techniques. The Al/Carmoisine/p-Si device exhibits good rectifying behaviour, with an ideality factor value of 1.547, indicating that the Carmoisine azo dye used as the interface material enhances the junction's performance and reduces the ideality factor. Barrier height (BH) parameters are calculated to be 0.770 eV, 0.733 eV, and 0.799 eV using the lnI-V, Cheung, and Norde techniques, respectively. The interfacial dipole created by passivation of the film causes the Carmoisine interlayer to raise the BH, resulting in an improved interface region for Al/p-Si structures. The extracted interfacial level concentration (N_ss) of the Al/Carmoisine/p-Si junction is lower than that of the Al/p-Si contact, indicating that the Carmoisine dye molecule reduces the N_ss value. Furthermore, the reverse bias 1/C²-V characteristic is employed to analyze the barrier height values and compare the findings to those from the IV method. The results show that the thin Carmoisine azo dye layer decreases leakage current and defect-trapped charge density, enhancing the reliability and performance of the devices. This study contributes a new organic electronic material, Carmoisine dye, to the literature on semiconductor devices.
Effects of potassium dichromate on the structural, linear/nonlinear optical properties of the fabricated PVA/PVP polymeric blends: For optoelectronics
2023, Materials Science and Engineering: B
The role of thin films in the optical field has received increased attention across several disciplines. In this present work, the synthesis of composite films of different potassium dichromate (K₂Cr₂O₇)-doped Polyvinyl alcohol/Polyvinyl pyrrolidone (PVP/PVP) blend polymer was achieved using the solution casting method. According to XRD analysis, the semi-crystallinity nature of PVA/PVP was evaluated, where the primary peak intensity was also varied as the K₂Cr₂O₇ wt% increased. In contrast, FT-IR investigations illustrated a strong peak in all K₂Cr₂O₇: PVA/PVP films assigned to asymmetric stretching vibration (CH). An increment in the absorption spectra was enhanced with the high doping contents of K₂Cr₂O₇ on the PVA/PVP blend polymer, where vice versa was observed in the transmission spectra. Urbach, direct and indirect optical energies were obtained to be symmetrically decreased with increasing K₂Cr₂O₇ weight concentrations in the host PVA/PVP blend polymer. Based on the energy bandgap, seven empirical, theoretical relations were proposed to optimize the linear refractive index. An increase in the nonlinear optical parameters for the addressed polymers was observed with the wt% increase of K₂Cr₂O₇. The proposed polymeric films of K₂Cr₂O₇ with PVA/PVP would be a unique optical potential system for different technical applications in optoelectronics, optical filters, laser limiters, and biomedical laser.
High optical performance of Gd<inf>2</inf>O<inf>3</inf>-doped PVA/PVP composite films for electronic and laser CUT-OFF filters
2022, Optik
Developing new composite materials with significant features is required for essential research and applications in many fields. The blend of the hydrophilic polymeric composites was considered as host carriers for significant rare-earth sources of Gd₂O₃ at various concentrations (0.05–9.87 wt. %) using the solution casting method. X-ray diffraction (XRD) ascertained the structural behavior of the prepared polymeric films, while the impressive Fourier transform-infrared (FT-IR) analysis landmark the existence of the O-H group on the PVA/PVP polymers. The extraordinary effects of different ratios of Gd₂O₃ dopants on the optical characteristics of the synthesized composite films were investigated using a UV–vis spectrophotometer. The transmittance spectra of pure PVA/PVP polymeric composites have been recorded to be 90 % in the visible region, then decreased to 66 %, increasing the Gd₂O₃ concentrations. Also, the absorption spectra of the examined Gd₂O₃-doped PVA/PVP films peak at 212 nm, revealing the π-π transition of blend segments. Furthermore, adding the Gd₂O₃ rare-earth dopants to the PVA/PVP polymers raised the bandgap energy and extinction coefficient values. Several theoretical models were applied to accurately evaluate the linear refractive index (n) and nonlinear optical parameters based on the prepared polymeric films' optical energy bandgaps (Eg). This research highlighted some outcome advantages of the semi-crystalline structure, outstanding linear optical energy bandgaps, refractive indexes, dielectric constant, optical limiting, and nonlinear optical properties of the proposed Gd₂O₃-doped PVA/PVP nanocomposite polymeric films. In conclusion, the synthesized Gd₂O₃ rare-earth source with a blend of PVA/PVP composites has vital influential and promising roles in practical optoelectronics and cut-off filters.

View all citing articles on Scopus

View full text

Rectification and barrier height inhomogeneous in Rhodamine B based organic Schottky diode

Abstract

Introduction

Section snippets

Materials

Processes and fabrication of the Al/Rh.B device

Thermogravimetry analysis and X-ray diffraction of Rh.B

Conclusion

Dyes Pigments

Appl. Surf. Sci.

Microelectron. J.

Synth. Met.

Synth. Met.

Dyes Pigments

Appl. Surf. Sci.

Appl. Surf. Sci.

Appl. Surf. Sci.

Physica B

J. Alloys Compd.

Synth. Met.

Microelectron. Eng.

J. Alloys Compd.

Polymers

Thin Solid Films

Int. J. Hydrogen Energy

Microelectron. Eng.