Exploring the optical and morphological properties of metal oxide thin films produced via reactive electron beam evaporation

Abstract

We report on the development of metal oxide films with potential applications in energy conversion devices. Using an electron beam evaporator in an oxygen atmosphere, titanium, tin, nickel, molybdenum and aluminum oxides in room temperature were reactively deposited. The deposited films were characterized optically and structurally using ultraviolet–visible (UV–Vis) spectrometry, ellipsometry, X-ray photoelectron spectroscopy (XPS), contact angle and scanning electron microscopy. A systematic comparison between these filters confirmed that stacking layers with titanium dioxide (TiO2) and nickel oxide (NiO) are the best candidate for PV modules as they demonstrate higher transmission in the visible range. The morphological analysis confirms the formation of compact, uniform, and defect-free metal films, as validated by field emission scanning electron microscopy (FESEM). Additionally, contact angle measurements were conducted to assess the wettability of the metal surfaces. All oxide films exhibited semi-hydrophilic characteristics, indicating their ability to repel water from the surface and suggesting improved stability. The stoichiometry was impacted by the varying oxygen pressures at which each oxide was deposited. The transmittance of the TiO2 and NiO are more than 80% in the visible range. The results investigate potential applications as antireflection coatings, high reflectance mirrors and selective filters.

Keywords:

• Metal oxide films
• reactive evaporation
• optical filters
• and energy conversion devices

Reviewing Editor:

• Ian Phillip Jones, University of Birmingham, United Kingdom of Great Britain and Northern Ireland

Subjects:

• Nanoscience & Nanotechnology
• Materials Science
• Manufacturing Engineering

Introduction

Thin films of metal oxides find extensive use in microelectronic and optoelectronic devices owing to their suitable empirical properties (Hinczewski et al., 2005; Shou et al., 2012; Lien et al., 2006; Sobczyk-Guzenda et al., 2009; Newman et al., 2007; Aïssa & Hossain, 2024; Hossain & Mansour, 2023; Hossain, Al Kubaisi, et al., 2022; Hossain, Ali, et al., 2022; Hossain, Khandakar, et al., 2022; Hossain, Zakaria, et al., 2022; Chelvanathan et al., 2017; Hossain & Alharbi, 2013; Grancini et al., 2017; Piegari & Flory, 2018). Titanium oxide (TiO_x) is a well-known material due to its optical, electronic and stable property. Various research groups have reported the growth optimization of TiO_x films for optical interference thin-film filters (Hinczewski et al., 2005; Shou et al., 2012; Lien et al., 2006). Also, photocatalytic effect has been explored for such films (Sobczyk-Guzenda et al., 2009). As expected, the needs of suitable TiO_x films properties are the key to design light-thin film interactive devices is the key (Newman et al., 2007; Aïssa & Hossain, 2024). Fluorine-doped tin oxide (SnO_x) is a well-known oxide material to be used as reflector due to its suitable optical properties (Hossain & Mansour, 2023). On the other hand, Al_xO_y, NiO_x and molybdenum oxide (MoO_x) have been explored as suitable materials to design filters as a specific part of light wavelengths can be tuned while blocking the rest (Hossain, Al Kubaisi, et al., 2022; Hossain, Ali, et al., 2022; Hossain, Khandakar, et al., 2022; Hossain, Zakaria, et al., 2022; Chelvanathan et al., 2017; Hossain & Alharbi, 2013). Many reports have confirmed the use of these kinds of metal oxide films for selective carrier transport because of having suitable electronic properties (Mwamburi et al., 2004; Jiang et al., 2001; Saraf et al., 2014; Jiang et al., 2001; Lee et al., 2009; Wisitsoraat et al., 2009; Chen et al., 2005; Ripin et al., 1999; Green et al., 2014; Kumar et al., 2016). Furthermore, room temperature deposition makes metal oxide films CMOS compatible with any upstream devices. Another benefit of these films is that they can be used for encapsulation/protection from moisture. The development of thin metal oxide films is crucial for various applications in photovoltaic (PV) cells. These films serve as electrical components within PV cells, act as passivation layers to safeguard against moisture and function as optical components with diverse roles such as antireflection (AR) coatings, high reflectance coatings/optical mirrors and various types of filters. Beyond morphological characteristics like uniformity and homogeneity, the refractive index of these films plays a significant role in determining spectral transmission, absorption and reflection of incident light. Hence, precise control and understanding of the properties of metal oxide films are essential for optimizing the performance of PV devices. Our study has showcased the feasibility of creating cost-effective nanofilms composed of economical oxide materials. This innovative technology not only provides increased stability through layer stacking, thereby presenting potential cost savings in large-scale manufacturing processes.

In general, the growth of inorganic n-type or p-type oxide materials at low temperatures within physical vapor deposition (PVD) process tools offers several advantages, including reduced device fabrication costs and enhanced device stability due to increased resistance to moisture. Among the various inorganic carrier transport materials, only a select few metal oxide materials have demonstrated the ability to meet operational device requirements. These materials include TiO_x, SnO_x, MoO_x and nickel oxide (NiO). Achieving high carrier mobility and establishing a pristine electrical interface with the absorbing layer are crucial prerequisites for minimizing carrier recombination within the device.

The formation of various oxides of titanium (Ti), tin (Sn), molybdenum (Mo), nickel (Ni), and aluminum (Al) in an oxygen (O₂) environment is influenced by several factors, including the chemical properties of the metal and the conditions under which the oxidation occurs. Each metal exhibits different oxidation behaviors due to variations in their electronic configurations and reactivity with oxygen. Titanium readily forms titanium dioxide (TiO₂) when exposed to oxygen at elevated temperatures. This oxide layer provides excellent corrosion resistance and is often used as a protective coating. The formation of TiO₂ typically occurs through a combination of direct oxidation and diffusion of oxygen into the metal lattice. The formation of SnO₂ oxides depends on factors such as temperature, oxygen concentration, and the presence of other substances. SnO is often formed under reducing conditions, while SnO₂ is the more stable oxide and forms under oxidizing conditions. MoO₂ typically forms at lower temperatures and is more stable under reducing conditions, while MoO₃ forms at higher temperatures and in the presence of excess oxygen. Nickel can form various oxides, including nickel(II) oxide (NiO) and nickel(III) oxide (Ni₂O₃), depending on the oxidation conditions. NiO is the most common oxide and forms when nickel is exposed to oxygen at moderate temperatures. The formation of Ni₂O₃ requires higher temperatures and is less common. Aluminum forms a protective oxide layer of aluminum oxide (Al₂O₃) when exposed to oxygen. This oxide layer is highly stable and prevents further oxidation of the underlying metal. The formation of Al₂O₃ occurs through the reaction of aluminum with oxygen in the air, resulting in the formation of a thin, transparent oxide layer.

AR coatings were the earliest applications for thin films and serve as an interface between two media with different refractive indices. For PV applications one medium is air with practically unity refractive index, while the second medium is a substrate like germanium, silicon or some semiconducting compound with a higher refractive index than air. Very simply, the AR coating must reduce reflection and ideally increase transmittance. These can be made from single layers with theoretically zero reflectance at a single wavelength to multilayered coatings with virtually zero reflectance over a range of wavelengths (Sobczyk-Guzenda et al., 2009; Aïssa & Hossain, 2024; Hossain & Mansour, 2023; Hossain, Ali, et al., 2022; Hossain, Al Kubaisi, et al., 2022; Hossain, Khandakar, et al., 2022) of equal importance to AR coatings are optical components that near-perfectly reflect incident light at certain wavelengths. Additionally, for more advanced applications, the transmittance through the optical component should be extremely low. Metal layers can provide acceptably high reflection for many applications but for advanced applications, the absorptance of light is unacceptably high. The addition of stacks of dielectric layers to metal reflectors can improve the performance of the mirrors while also reducing absorptance in the metal layers.

For filter applications where light that is not reflected is transmitted stacks of dielectrics have found widespread applications. The Fabry Perot interferometer is one such component made of all-dielectric layers. To optimize the reflection and or transmission through dielectric stacks, thin films of different dielectric constants and thicknesses are used. Software optimization routines are employed to tune the stacks over different parts of the spectrum. Usually, two materials – one with a high refractive index and the other with a low index – make up the dielectric stacks.

Various filter applications utilizing these metal oxide layers for study (Hinczewski et al., 2005; Shou et al., 2012; Lien et al., 2006; Sobczyk-Guzenda et al., 2009; Newman et al., 2007; Aïssa & Hossain, 2024; Hossain & Mansour, 2023; Hossain, Zakaria, et al., 2022; Hossain, Ali, et al., 2022; Hossain, Al Kubaisi, et al., 2022). However, few issues need to be focused before lodging in full scale such as the pristine growth of the layers in addition to the best match optical properties of such films. Such thin films can be created using several PVD processes like sputtering (Kumar et al., 2016; Ye et al., 2017; Salado et al., 2017; Rao et al., 2015; Ye et al., 2017; Zhao et al., 2014), evaporation (Tseng et al., 2016; You et al., 2016; Chen et al., 2017; Wang et al., 2013; Pinpithak et al., 2016) and atomic layer deposition (ALD) (Liu et al., 2017; Cao et al., 2015; Hossain et al., 2015; Alfihed et al., 2013).

This study introduces a method for depositing metal oxides through reactive deposition using electron beam (e-beam evaporation) of pure metals within a controlled oxygen environment (Tokas et al., 2023). Metal oxide layers play a crucial role in PV applications, contributing to the efficiency and stability of solar cells. These layers serve various functions, including passivation of surfaces, charge transport facilitation, and enhancement of light absorption. For instance, metal oxide thin films, such as TiO₂ is commonly used as electron transport layers (ETLs) or hole-blocking layers in different types of solar cells. These materials help to efficiently transport charge carriers while preventing recombination at the interface between the active layer and the electrode. Additionally, metal oxide layers can be engineered to exhibit desired optical and electrical properties, such as high transparency, low resistivity, and suitable band alignment with the adjacent layers in the device. Through careful design and optimization, metal oxide layers contribute to improving the performance, reliability and longevity of PV devices, thereby advancing the development of sustainable energy technologies.

Furthermore, e-beam evaporation offers the advantage of creating n-i-p or p-i-n structures without disrupting the vacuum, facilitating the fabrication of high-efficiency devices. However, it becomes imperative to fine-tune the growth of ETL or hole transport layer (HTL) to achieve optimal optical and electrical properties. Perovskite, a commonly used light-harvesting layer, is vulnerable to moisture absorption, leading to the degradation of cation and anion sites and resulting in films with high defect concentrations and poor PV performance. Therefore, developing inorganic ETL and HTL layers with hydrophobic properties is crucial to encapsulate the perovskite layer and shield it from water molecules, ensuring its stability.

In this study, e-beam evaporation was employed to deposit oxide films by adjusting the oxygen flow rate during film deposition, which correlates with the deposition-chamber pressure. The selection of e-beam evaporation was motivated by its ability to precisely control the deposition rate and its suitability for large-scale device fabrication without breaking the vacuum. This capability enables the development of the entire device structure in a moisture-free environment, thereby averting any potential performance degradation. The investigation focused on assessing the impact of oxygen pressure on the microstructure, surface morphology and optical properties of the metal oxide layers. Optical spectroscopy techniques, including absorption coefficient, absorbance, and ellipsometry, were employed to determine the film bandgaps. The analysis of the obtained data revealed a discernible correlation between surface morphology and different deposition pressures.

As studied previously, one of the works considers the structural, optical, electrical and micro morphological properties studies thoroughly for reactively e-beam evaporated and annealed metal-oxide thin films grown at different pressures of oxygen. However, the results were limited as the films require higher processing temperature which makes it difficult to develop films on flexible substrates.

The technique provides precise control over the deposition rate, ensures uniform deposition across samples, allows flexibility in depositing various materials, and facilitates adjustment of the relative oxygen-to-metal concentration. The effects of oxygen pressure on the optical properties and surface structure of evaporated thin films have been investigated for a range of metal content films. Using an integration of ellipsometer and UV–Vis data, the optical bandgaps of the films have been measured. Variable angle spectroscopic ellipsometry was used to determine optical characteristics, such as refractive indices (n) and extinction coefficients (k). These optical parameters were subsequently utilized in designing components for antireflective coatings, high-reflectance mirrors, and filters, with applications tailored to the interests in PV solar cells.

Methodology

First, acetone and isopropanol were used as solvents to clean soda lime glasses (SLG), and then each ultrasonic cleaning session lasted five minutes with deionized water. The glass slides underwent nitrogen gas flow blow drying. Three distinct oxygen pressures were used for the evaporation: 2 × 10⁻⁴, 2 × 10⁻⁵ and 9 × 10⁻⁵ Torr. Denton^™ Explorer e-beam evaporator was used for the process and room temperature was used for the deposition. Kurt J. Lesker provided Mo, Ni, Ti, Ni and Al evaporation pellets with a 4N5 purity. A cryo pump was used to lower the base pressure of the deposition chamber to 10⁻⁶ Torr. Table 1 reports the parameters of evaporation. To prevent oxidation, every room temperature film was maintained in a vacuum inside the chamber utilizing a natural cooling technique. The JEOL SEM 7610^™ was used for the morphological and EDS investigation, the Stylus profilometer has been used to quantify film’s thickness, and The Ellipsometer and UV–Vis spectroscopy (Jasco V100^™) were utilized to investigate the optical properties of the annealed films.

Table 1. Standard metal oxide thin-film evaporation conditions.

Parameter	Deposition requirement	Deposition requirement	Deposition requirement	Deposition requirement	Deposition requirement
Pellets	Ti (99.999% pure)	Sn (99.995% pure)	Mo (99.995% pure)	Ni (99.995% pure)	Al (99.995% pure)
Deposition Pressure (Torr)	2 × 10^−4	2 × 10^−4	2 × 10^−4	2 × 10^−4	2 × 10^−4
	9 × 10^−5	9 × 10^−5	9 × 10^−5	9 × 10^−5	9 × 10^−5
	2 × 10^−5	2 × 10^−5	2 × 10^−5	2 × 10^−5	2 × 10^−5
Deposition rate (A/s)	1	1	1	1	1

The optical properties and thickness of the thin metal oxide thin films were measured at a 65° angle of incidence and in the wavelength range of 190–2100 nm (0.6–6.5 eV) using the HORIBA Scientific UVISEL2 Spectroscopic Ellipsometer. Phase modulation technology is the foundation of this ellipsometer. The signal provides a high signal to noise ratio of data due to its two photomultipliers for UV–VIS band detection. Additionally, because it is modulated at a high frequency of 50 kHz, more data may be averaged. The infrared detector is made with semiconductors made of InGaAs. The two-layer model that described the sample was enhanced by adding a rough over layer to increase fitting at the top of the primary layer. The Bruggeman Effective Medium Approximation defines this coarse layer, which is composed of 50% metal oxide and 50% vacuum. The data were fitted with the classical model, which consists of a single oscillator and a Drude term. This allowed the dispersions of the optical constants of the films to be characterized throughout the complete spectrum. Structural properties were examined using a XPS Escalab 250Xi (Thermo Fisher Scientific^™, Waltham, MA). XPS spectra were analyzed and fitted using Avantage software, utilizing monochromatic Al K alpha as the source with an energy of 1486.68 eV. A pass energy of 20 eV was used for all narrow scans and 100 eV for survey scans, with 10 scans performed for high-resolution spectra and 1 scan for survey spectra. Surface morphology was investigated using a JEOL SEM 7610^™, and optical properties of the films were examined via UV–Vis spectroscopy (Jasco V100^™). Hydrophobicity and hydrophilicity of the films were characterized using a Kruss contact angle measurement tool.

Results and discussion

Chemical properties of the thin films

Figure 1 depicts the X-ray photoelectron spectroscopy (XPS) analysis, which was fitted using Avantage software. The excitation source utilized was Al K alpha, with an energy of 1486.68 eV, and a pass energy of 20 eV for all narrow scans and 100 eV for survey scans. Each high-resolution spectrum comprised 10 scans, while a single survey spectrum was conducted. The survey spectrum revealed the growth of pristine oxide films with minimal carbon contamination. It was observed that deposition pressure significantly influenced the transformation of the surface into an oxidized phase. Samples confirmed stoichiometric growth without any foreign contamination. For our study, only these four metal oxide films at 2 × 10⁻⁴ Torr were considered to investigate the conformity of deposition.

Figure 1. XPS survey of metal oxide films with 100 nm thickness.

The surface morphological properties of metal oxide thin films

Field emission scanning electron microscopy (FESEM) is a very useful technique for determining the shape, size, microstructure, growth mechanism and form of the films. FESEM was utilized for examining and investigating surface morphology. To prevent any loss of light, the film needs to be continuous, void-free, packed full of big particles and seamlessly blended. There must be a nominal density of crystalline flaws in the film’s microstructure. To examine the surface morphology, 100 nm scale FESEM pictures have been obtained. Figure 2 shows the FESEM images of the annealed thin films produced at 2 × 10⁻⁴ Torr pressure. The unique and differentiable surface morphological characteristics of the thin films generated at pressures can be recognized. The films appear to be pinhole-free and compact throughout all regions based on the FESEM pictures. This surface morphology validates the homogeneity in addition to the films’ optimal deposition. In the FESEM pictures, a specific structure and surface morphology were identified for every film. The thin films with thick surfaces were interacting with the grains. The deposited films completely enclose the substrates and were discovered to be crack-free. The creation of filters with ideal growing conditions is made possible by these findings.

Figure 2. FESEM images of thin films produced at 2 × 10⁻⁴ Torr at 100 nm of scale.

To maximize the power conversion efficiency of solar cells, it is essential for the oxide films to exhibit uniformity, with no voids or discontinuities, and to contain large particles or grains. An ideal microstructure for the film would have minimal crystalline defects. This uniformity is critical for ensuring optimal electrical properties in devices utilizing such films. Furthermore, the oxidation process enhances the transparency of the films. Thus, by adjusting the oxygen content within the chamber, the stoichiometry of the films can be precisely controlled. These findings hold promise for optimizing the fabrication of PV devices by incorporating suitable metal-oxide layers as buffer materials to enhance interface quality.

The metal oxide thin films’ optical properties

The annealed materials’ optical properties between 350 and 800 nm were investigated using UV–Vis spectroscopy. The separation of metal-rich and metal-poor films in clean samples is supported by transmission and absorbance measurements (Figures 3 and 4). The highest transmission and lowest absorption for all oxide films are observed in the visible spectrum produced at 2 × 10⁻⁴ Torr deposition pressure. The transmittance of oxide films typically increases with increasing pressure due to the densification and improved crystallinity of the films under higher pressure conditions. Higher pressure during deposition promotes the packing of atoms or molecules in the oxide film, leading to increased density (Tien et al., 2018). Denser films have fewer voids and defects, resulting in improved optical properties such as higher transmittance. Higher pressure conditions can facilitate the growth of larger crystallites within the oxide film. Enhanced crystallinity reduces scattering of light within the film, allowing more light to transmit through the material, thereby increasing transmittance. Increased pressure during deposition can help minimize the formation of porosity or voids within the oxide film. Porous films tend to scatter and absorb light, reducing transmittance. By reducing porosity, higher pressure deposition leads to smoother and more transparent films, resulting in higher transmittance (Tien et al., 2018). The spectra show the significant change as a function of deposition pressure. Transmission and absorbance in polycrystalline semiconductors can be affected by the stoichiometric deviation, the quantum size effect and the disorder at grain boundaries.

Figure 3. The transmission spectra of three distinct pressure-deposited metal oxide coatings.

Figure 4. The transmission spectra of three distinct pressure-deposited metal oxide coatings are presented.

Using the Tauc curve to match the data on optical absorption, the bandgap data is produced.

The following equation has been used to compute the absorption co-efficient. $$\alpha \left(\mathit{\text{hf}}\right)=A{\left(\mathit{\text{hf}}-E_g\right)}^{0.5}$$

In this case, hf stands for photon energy, E_g for bandgap energy, and α is the coefficient. Figure 4 depicts an absorption coefficient vs. photon energy graph. For a semiconductor E_g(eV). A Tauc plot, also known as a Tauc plot analysis or Tauc plot method, is a graphical technique used to determine the optical bandgap of a material from its absorption spectrum. The Tauc plot is constructed by plotting the square of the absorption coefficient (α) as a function of the photon energy (hν) or wavelength (λ). In the Tauc plot, the absorption edge of the material corresponds to the onset of a sharp increase in the absorption coefficient. This onset point is extrapolated back to the x-axis (hν = 0 or λ = ∞), and the intercept provides an estimation of the optical bandgap energy (Eg) of the material.

The bandgap energy is obtained by extrapolating the figure’s straight-line component to the zero absorption coefficients, as illustrated in Figure 5. Bandgap fluctuation is primarily caused by the significant dependency of electronic states on the mass of the effective exciton. Moreover, it is subject to fluctuations in quantum confinement, dielectric confinement and bandwidth. The graphic illustrates each film’s bandgap variation at three different deposition pressures. The primary correlation between relaxed lattice strain and relaxed crystal growth is the reduction of metal-rich oxide films’ bandgap. The attenuation coefficient and refractive index of the annealed samples were also measured using an ellipsometer. Figure 6 shows the measured values of the refractive index (n) and attenuation coefficient (k) for the films deposited at various pressures. It shows that films rich in metals have a higher k value at 632 nm, suggesting that the increased absorption is caused by the formation of metallic droplets. This phenomenon is mostly caused by the creation of metallic droplets at the 2 × 10⁻⁵ Torr deposition pressure, where the oxygen flow rate is limited. Furthermore, almost all the films had a refractive index value that was high (n > 2), which is definitely advantageous for PVs.

Figure 5. The absorbance coefficients of four metal oxide coatings at three different deposition pressures are shown in the spectra.

Figure 6. Five metal oxide films at three distinct deposition pressures are shown by their refractive index and extinction co-efficient.

Hydrophobic properties of the metal-oxide thin films

The hydrophobic properties of the metal-oxide thin films are crucial, as they influence the condensation behavior of water droplets on the surface. Figure 7 illustrates varying trends in hydrophobicity among different metal oxides. Typically, minimizing the substrate’s influence is necessary to achieve hydrophobicity, as greater surface tension tends to shift the interaction toward super hydrophilicity.

Figure 7. Contact angle measurement of five metal oxide films grown at 2 × 10⁻⁴ Torr.

Conclusion

In this study, we utilized a reactive e-beam evaporation process to create mono layers consisting of metal oxides layers. TiO₂ and NiO layers yielded the highest transmittance (T %) above 80% in the visible range. Subsequently, the development anticipated additional functionalities such as AR and anti-soiling coatings. These results affirm that the developed metal-oxide layers, manufactured through thermal e-beam evaporation, can function as carrier transport materials with potential anti-dust properties and suitability for large-scale production. Extensive research has been conducted on the structural properties of evaporated metal oxide thin films, encompassing the lattice parameter, crystal orientation and grain size generated at different pressures. By improving photon scattering and refining reflection, these oxide films preserve the space for optical filters and anti-reflection coatings in PV applications. The films were compact in every area, as shown by the FESEM images, and they were free of pinholes, which is very desirable. The films’ surface morphology is strongly influenced by the deposition pressure, as the FESEM images demonstrate, a smoother surface result from a slower deposition rate. The correlation between poor/rich oxygen films and optical characteristics is confirmed by optical measurements of samples generated under various process conditions. Ongoing research endeavors are directed toward accurately quantifying this temperature reduction and establishing correlations with varying dusty and meteorological conditions. Additionally, the future development should consider the design of a device achieving optimal performance could be achieved by carefully selecting electron transport material (ETM) and hole transport material (HTM) layers with optimal optical properties while minimizing defects in the bulk and interfaces. The optimized layers should be directly utilized as large scale solar cell carrier transport layers.

Author contribution

Mohammad Istiaque Hossain: Data curation, Formal analysis, Investigation, Methodology, Validation, Visualization, Roles/Writing - original draft.

Brahim Aissa: Supervision, Validation.

Amith Khandakar: Writing - review & editing.

Kevin Thomas: Writing - review & editing.

Ahasanur Rahman: Writing - review & editing.

Said Mansour: Project administration, Resources, Supervision.

Disclosure of interest

There are no interests to declare.

Acknowledgments

Open Access funding provided by the Qatar National Library.

Data availability statement

The data that support the findings of this study are available from the corresponding author, [MIH], upon reasonable request.

Additional information

Notes on contributors

Mohammad Istiaque Hossain

Dr. Mohammad Istiaque Hossain is working as a Scientist at HBKU core Labs with a focus to develop thin films for energy applications.

Brahim Aissa

Dr. Brahim Aissa is working as a Senior Scientist at QEERI with a focus to develop thin films for energy applications.

Amith Khandakar

Dr. Amith Khandakar is working as a Researcher at QU with a focus to develop thin films for energy applications.

Kevin Thomas

Mr. Ahasanur is a PhD student at Qatar University.

Ahasanur Rahman

Mr. Kevin is a PhD student at Qatar University.

Said Mansour

Dr. Said Mansour is the director of HBKU core labs.