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Quantum efficiency enhancement by employing specially designed AlGaN electron blocking layer
Journal Pre-proof Quantum efficiency enhancement by employing specially designed AlGaN electron blocking layer Muhammad Usman, Munaza Munsif, Abdur-Rehman Anwar, Habibullah Jamal, Shahzeb Malik, Noor Ul Islam PII:
S0749-6036(19)32103-2
DOI:
https://doi.org/10.1016/j.spmi.2020.106417
Reference:
YSPMI 106417
To appear in:
Superlattices and Microstructures
Received Date: 9 December 2019 Revised Date:
15 January 2020
Accepted Date: 24 January 2020
Please cite this article as: M. Usman, M. Munsif, A.-R. Anwar, H. Jamal, S. Malik, N.U. Islam, Quantum efficiency enhancement by employing specially designed AlGaN electron blocking layer, Superlattices and Microstructures (2020), doi: https://doi.org/10.1016/j.spmi.2020.106417. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd.
Quantum efficiency enhancement by employing specially designed AlGaN electron blocking layer Muhammad Usmana*, Munaza Munsifa, Abdur-Rehman Anwara, Habibullah Jamala, Shahzeb Malika, Noor Ul Islama a
Faculty of Engineering Sciences, Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi, 23460, Khyber Pakhtunkhwa, Pakistan. (e-mail: [email protected])
Abstract: Green light-emitting diodes light-emitting diodes with specially designed AlGaN electron blocking layer are numerically investigated. Examination of simulation results shows that applying proposed electron blocking layers, the injection of holes inside the active region can be improved. The improved performance for LEDs with specially designed AlGaN electron blocking layer is illustrated through the simulated results i.e. energy band diagrams, distribution of hole concentration and rate of radiative recombination inside the active region. The LEDs with graded AlGaN EBL have considerably enhanced light output power (LOP) and internal quantum efficiency. Introduction: III-Nitrides have emerged as a promising optoelectronic material for light-emitting diodes (LEDs) and laser diodes (LDs) [1]. Because of the multifold advantages these devices, applications like traffic signals, automobile headlights, displays, cell phone backlights and printers have been attainable [2, 3]. GaN-based blue LEDs with peak internal quantum efficiency (IQE) of up to 90% and green LEDs with peak IQE of up to~60% have been reported [4]. This severe decline of efficiency in the green region of visible spectrum from III-V semiconductors is referred to as “green gap” [5-7]. For the emission of green light, high composition of indium (In) is required in active InGaN layer which also initiates issues like “efficiency droop” in green LEDs [3, 8, 9]. This major problem still prohibits further involvement of LEDs into immense power applications. Several phenomena have been suggested to explain the reasons behind the efficiency droop [10-13]. However, determining the exact origin of efficiency droop is still under consideration [14]. Different LED structures have been reported to reduce the above discussed phenomenon [15-21]. One of the leading causes of efficiency droop is the presence of strong electrostatic field in the active region because of the large lattice mismatch in c-oriented samples and the higher mobility of electrons in comparison to that of holes [22]. This asymmetry leads to known electron leakage. The common solution to reduce electron leakage is to insert AlGaN electron blocking layer (EBL) layer in between last barrier and p-GaN layer. This AlGaN layer acts as an additional barrier not only in the path of electron overflow but also in the path of hole injection [23, 24]. In practice, the presence of large lattice mismatch between last barrier and EBL creates piezoelectric polarization field. The polarization field pulls the conduction and valence band downwards at the last barrier/EBL interface and therefore, both the overflow of electrons and injection of holes is markedly affected [25, 26]. Different techniques have been reported to make efficient EBLs by enhancing the blockage of electrons and transportation of holes. By
employing AlInGaN quaternary EBL, reduction is observed in built-in charge density at the interface [23, 27]. Electron confinement is also improved by inserting ternary AlInN EBL [28]. Besides this many other designs of EBL are also reported e.g. employing n-AlGaN EBL [29]. Blue LEDs with graded AlGaN EBL are reported by Kuo et al in which the composition of Al is graded from 0 to 15% [30]. Curbing the electron overflow and enhancing the transportation of holes is the goal in all these proposed structures. Hence it is very important to explore further novel graded EBL structures to enhance the performance of, especially green, LEDs. In this study, specially designed AlGaN EBL structures are proposed to augment the device output. Device Structure The electrical and optical properties of InGaN/GaN conventional LED and proposed LEDs with designed EBL are studied numerically using APSYS [31]. In this study four LEDs structures have been investigated. All LEDs emit light in the green region of spectrum. LEDA (conventional LED) consists of 5 InGaN quantum wells (QWs) cladded by 6 GaN quantum barriers (QB). InGaN QW is 2.6 nm thick with 30% composition of indium while GaN QB has a thickness of 8.5 nm, the thickness of EBL is 20 nm with 10% aluminum (Al) composition while the p- doping concentration in AlGaN is 5 × 1017 cm-3. n-GaN layer has thickness of 200 nm with 5 × 1018 cm-3 doping concentration and for pGaN layer thickness and doping concentration are 150 nm and 1 × 1018 cm-3 respectively. The device geometry is 300 × 300 µm2. LEDB has same device structure as LEDA except EBL whose one side (towards last QB) is step graded while other side (towards p-GaN) is linearly graded. LEDC is same as LEDA (conventional structure) except that its EBL is mirror image of EBL of LEDB. Schematics of the devices are shown in Fig.1.
(a)
Fig.1. Schematic of (a) conventional LED (b) electron blocking layers (EBLs) of LEDA, LEDB and LEDC.
Results and Discussions
(b)
(a)
(c) Fig.2. Calculated band diagrams of LEDA, LEDB and LEDC before current injection.
Fig.2(a), (b) and (c) are representing the energy band diagrams of LEDA (conventional structure), LEDB and LEDC (proposed structures). Fig.2(a) represents the energy band diagram of LEDA. It can be clearly observed from the figure that the effective barrier height for holes is higher i.e. 740 meV. This is because of the presence of large lattice misalignment between GaN (QB) and AlGaN (EBL). Due to such large lattice misalignment band bending is noticed between EBL and last QB because of the existence of the spontaneous and piezoelectric polarization. Holes because of their greater effective mass, lower mobility and such high potential barrier will be hindered and their tunneling into the active region is reduced, they are easily trapped inside the narrow bent between QB/EBL interface. Fig.2(b) shows the energy band diagram of LEDB. From the figure, it can be noticed that by inserting graded EBL in the device band bending is decreased and an effective barrier height is
decreased significantly i.e. up to 696 meV which increases the chance of insertion of holes into the active region. Fig.2(c) represents the energy band diagram of LEDC. In LEDC, the graded EBL is the mirror image of LEDB as discussed above. Here at last QB/EBL interface energy of valence band is decreased i.e. 655 meV. Consequently, the movement of holes into the active region is enhanced. Thus, the graded EBL is proved to be effective in reducing the negative effect of EBL on the movement of holes.
(a)
(b)
Fig.3 (a) concentration of electrons (b) concentration of holes inside the active region of all the devices at 40 A.cm-2.
Carrier concentration of three LEDs is shown in Fig.3. The electron concentration is nearly same in all the LEDs as shown in Fig.3(a). Here our focus is on the injection and confinement of holes inside the active region which is very critical in GaN based devices [25]. In general, there is a gradual decrease in concentration of holes from the QW which is closer to p-side then that one which is closer to n-side because of the lower mobility and greater effective mass of holes. The injection as well as confinement of holes into the active region is improved in LEDC in comparison to other two LEDs. In LEDC, among all the QWs, the most prominent increase in hole concentration is observed in QW closest to p-side i.e. ~35% in comparison to LEDA. The overall hole concentration is enhanced by 13% in LEDC than the conventional structure i.e. LEDA. The observed improvement in hole concentration is attributed to the reduced effective barrier height for holes as shown in Fig. 2. So, the issue of hole confinement has been reduced in LEDC as shown in Fig.3(b).
Fig.4. The radiative recombination of all the LEDs within the active region of all the LEDs in comparison at 40 A.cm-2.
Fig.4. shows the calculated radiative recombination rates of all the LEDs. It can be seen clearly from the figure that similar radiative recombination trend, in terms of quantum wells, is shown by all the LEDs, i.e. the maximum radiative recombination of electrons with holes is carried out in last QW which is next to p-GaN layer [21, 25, 32, 33]. As discussed earlier, holes have higher effective mass and lower mobility which makes it difficult for holes to move within the active region. In comparison to the holes, lower effective mass and higher mobility of electrons allows electrons to move in the active region easily. The radiative recombination rate in QW closest to p-side of LEDC is enhanced up to ~63% as compared to LEDA. Overall, LEDC shows improved radiative recombination rate i.e. ~26% as compared to LEDA. The improved hole confinement in QWs and reduced barrier height for transportation of holes are the key factors in the enhancement of radiative recombination rate.
Fig.5. Spontaneous emission spectra of LEDA, LEDB and LEDC
Fig.5. represents the emission spectra of LEDA, LEDB and LEDC. All LEDs show peak emission spectra within the green region of visible spectrum i.e. ~ 525 nm. The broadening of full width at the half maximum (FWHM) is observed to be more in LEDC as compared to LEDA and LEDB. Besides FWHM, the peak emission spectra of LEDC is approximately doubled as compared to conventional
LED i.e. LEDA. The integrated emission spectra of LEDA, LEDB and LEDC are 4410.589 s-1eV-1, 5281.477 s-1eV-1, 7329.588 s-1eV-1 respectively. Therefore, LEDC shows maximum emission spectra as compared to LEDA and LEDB.
Fig.6. IQE (Normalized) and LOP of LEDA, LEDB and LEDC with respect to current density.
The dependence of IQE (η) and light output power (LOP) on injection current is demonstrated for all the LEDs in Fig.6. In comparison to the conventional structure i.e. LEDA, improved LOP is observed in other structures i.e. LEDB and LEDC. At 100 A/cm2, the LOP of LEDA, LEDB and LEDC is 68 mW, 83 mW and 117 mW respectively. So, in other words we can say that LOP of LEDC is enhanced up to ~42% and ~29% as compared to that of LEDA and LEDB respectively. The efficiency droop, ɳɳ
calculated as
/
ɳ
, is ~53%, ~43% and ~21% in LEDA , LEDB and LEDC respectively.
So, in our proposed structure not only the efficiency peak is increased but droop ratio is also decreased at high current density which is necessary for the enhancement of device properties. Conclusion In conclusion, InGaN-based LEDs with specially designed EBLs are investigated numerically. By inserting proposed graded EBL, better hole concentration is observed in the active region which is attributed to the decrease in valence band offset. Therefore, the suggested structure shows the overall improved radiative recombination rate, increased LOP and enhanced IQE peak as well as reduced droop ratio. To put it in a nutshell, our proposed structure is a better choice for high performance of InGaN-based green LEDs. Acknowledgements We are highly grateful to Semiconductor Photonics Laboratory, Hanyang University, South Korea for providing the needed resources.
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Dear Editor Superlattices and Microstructures
We believe that following are the highlights of our work.
1. In this work, we propose a special design of EBL layers to improve the device performance of GaN-based green light-emitting diodes. 2. Detailed comparison of optoelectronic properties of the reference and our proposed GaNbased light-emitting diodes has been presented 3. We believe that our proposed design may substantially improve the device performance, especially in the green emission range.
We look forward to your critical review and valuable reply.
Regards, Muhammad Usman, Ph.D. Ghulam Ishaq Khan Institute of Engineering Sciences & Technology Pakistan
Dear Editor
Author Statement:
Conceptualization;
Muhammad Usman, Abdur-Rehman Anwar
Data curation;
Abdur-Rehman Anwar
Formal analysis;
Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif
Funding acquisition;
N/A
Investigation; Malik, Noor Ul Islam
Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif, Shahzeb
Methodology;
Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif
Project administration;
Muhammad Usman
Resources; Jamal
Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif, Habibullah
Software;
Muhammad Usman, Abdur-Rehman Anwar,
Supervision;
Muhammad Usman
Validation; Malik, Noor Ul Islam
Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif, Shahzeb
Visualization;
Muhammad Usman, Abdur-Rehman Anwar
Roles/Writing – original draft; Muhammad Usman, Abdur-Rehman Anwar, Writing – review & editing. Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif, Habibullah Jamal, Shahzeb Malik, Noor Ul Islam
Regards, Muhammad Usman, Ph.D. Ghulam Ishaq Khan Institute of Engineering Sciences & Technology Pakistan
Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:
S0749-6036(19)32103-2
DOI:
https://doi.org/10.1016/j.spmi.2020.106417
Reference:
YSPMI 106417
To appear in:
Superlattices and Microstructures
Received Date: 9 December 2019 Revised Date:
15 January 2020
Accepted Date: 24 January 2020
Please cite this article as: M. Usman, M. Munsif, A.-R. Anwar, H. Jamal, S. Malik, N.U. Islam, Quantum efficiency enhancement by employing specially designed AlGaN electron blocking layer, Superlattices and Microstructures (2020), doi: https://doi.org/10.1016/j.spmi.2020.106417. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd.
Quantum efficiency enhancement by employing specially designed AlGaN electron blocking layer Muhammad Usmana*, Munaza Munsifa, Abdur-Rehman Anwara, Habibullah Jamala, Shahzeb Malika, Noor Ul Islama a
Faculty of Engineering Sciences, Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi, 23460, Khyber Pakhtunkhwa, Pakistan. (e-mail: [email protected])
Abstract: Green light-emitting diodes light-emitting diodes with specially designed AlGaN electron blocking layer are numerically investigated. Examination of simulation results shows that applying proposed electron blocking layers, the injection of holes inside the active region can be improved. The improved performance for LEDs with specially designed AlGaN electron blocking layer is illustrated through the simulated results i.e. energy band diagrams, distribution of hole concentration and rate of radiative recombination inside the active region. The LEDs with graded AlGaN EBL have considerably enhanced light output power (LOP) and internal quantum efficiency. Introduction: III-Nitrides have emerged as a promising optoelectronic material for light-emitting diodes (LEDs) and laser diodes (LDs) [1]. Because of the multifold advantages these devices, applications like traffic signals, automobile headlights, displays, cell phone backlights and printers have been attainable [2, 3]. GaN-based blue LEDs with peak internal quantum efficiency (IQE) of up to 90% and green LEDs with peak IQE of up to~60% have been reported [4]. This severe decline of efficiency in the green region of visible spectrum from III-V semiconductors is referred to as “green gap” [5-7]. For the emission of green light, high composition of indium (In) is required in active InGaN layer which also initiates issues like “efficiency droop” in green LEDs [3, 8, 9]. This major problem still prohibits further involvement of LEDs into immense power applications. Several phenomena have been suggested to explain the reasons behind the efficiency droop [10-13]. However, determining the exact origin of efficiency droop is still under consideration [14]. Different LED structures have been reported to reduce the above discussed phenomenon [15-21]. One of the leading causes of efficiency droop is the presence of strong electrostatic field in the active region because of the large lattice mismatch in c-oriented samples and the higher mobility of electrons in comparison to that of holes [22]. This asymmetry leads to known electron leakage. The common solution to reduce electron leakage is to insert AlGaN electron blocking layer (EBL) layer in between last barrier and p-GaN layer. This AlGaN layer acts as an additional barrier not only in the path of electron overflow but also in the path of hole injection [23, 24]. In practice, the presence of large lattice mismatch between last barrier and EBL creates piezoelectric polarization field. The polarization field pulls the conduction and valence band downwards at the last barrier/EBL interface and therefore, both the overflow of electrons and injection of holes is markedly affected [25, 26]. Different techniques have been reported to make efficient EBLs by enhancing the blockage of electrons and transportation of holes. By
employing AlInGaN quaternary EBL, reduction is observed in built-in charge density at the interface [23, 27]. Electron confinement is also improved by inserting ternary AlInN EBL [28]. Besides this many other designs of EBL are also reported e.g. employing n-AlGaN EBL [29]. Blue LEDs with graded AlGaN EBL are reported by Kuo et al in which the composition of Al is graded from 0 to 15% [30]. Curbing the electron overflow and enhancing the transportation of holes is the goal in all these proposed structures. Hence it is very important to explore further novel graded EBL structures to enhance the performance of, especially green, LEDs. In this study, specially designed AlGaN EBL structures are proposed to augment the device output. Device Structure The electrical and optical properties of InGaN/GaN conventional LED and proposed LEDs with designed EBL are studied numerically using APSYS [31]. In this study four LEDs structures have been investigated. All LEDs emit light in the green region of spectrum. LEDA (conventional LED) consists of 5 InGaN quantum wells (QWs) cladded by 6 GaN quantum barriers (QB). InGaN QW is 2.6 nm thick with 30% composition of indium while GaN QB has a thickness of 8.5 nm, the thickness of EBL is 20 nm with 10% aluminum (Al) composition while the p- doping concentration in AlGaN is 5 × 1017 cm-3. n-GaN layer has thickness of 200 nm with 5 × 1018 cm-3 doping concentration and for pGaN layer thickness and doping concentration are 150 nm and 1 × 1018 cm-3 respectively. The device geometry is 300 × 300 µm2. LEDB has same device structure as LEDA except EBL whose one side (towards last QB) is step graded while other side (towards p-GaN) is linearly graded. LEDC is same as LEDA (conventional structure) except that its EBL is mirror image of EBL of LEDB. Schematics of the devices are shown in Fig.1.
(a)
Fig.1. Schematic of (a) conventional LED (b) electron blocking layers (EBLs) of LEDA, LEDB and LEDC.
Results and Discussions
(b)
(a)
(c) Fig.2. Calculated band diagrams of LEDA, LEDB and LEDC before current injection.
Fig.2(a), (b) and (c) are representing the energy band diagrams of LEDA (conventional structure), LEDB and LEDC (proposed structures). Fig.2(a) represents the energy band diagram of LEDA. It can be clearly observed from the figure that the effective barrier height for holes is higher i.e. 740 meV. This is because of the presence of large lattice misalignment between GaN (QB) and AlGaN (EBL). Due to such large lattice misalignment band bending is noticed between EBL and last QB because of the existence of the spontaneous and piezoelectric polarization. Holes because of their greater effective mass, lower mobility and such high potential barrier will be hindered and their tunneling into the active region is reduced, they are easily trapped inside the narrow bent between QB/EBL interface. Fig.2(b) shows the energy band diagram of LEDB. From the figure, it can be noticed that by inserting graded EBL in the device band bending is decreased and an effective barrier height is
decreased significantly i.e. up to 696 meV which increases the chance of insertion of holes into the active region. Fig.2(c) represents the energy band diagram of LEDC. In LEDC, the graded EBL is the mirror image of LEDB as discussed above. Here at last QB/EBL interface energy of valence band is decreased i.e. 655 meV. Consequently, the movement of holes into the active region is enhanced. Thus, the graded EBL is proved to be effective in reducing the negative effect of EBL on the movement of holes.
(a)
(b)
Fig.3 (a) concentration of electrons (b) concentration of holes inside the active region of all the devices at 40 A.cm-2.
Carrier concentration of three LEDs is shown in Fig.3. The electron concentration is nearly same in all the LEDs as shown in Fig.3(a). Here our focus is on the injection and confinement of holes inside the active region which is very critical in GaN based devices [25]. In general, there is a gradual decrease in concentration of holes from the QW which is closer to p-side then that one which is closer to n-side because of the lower mobility and greater effective mass of holes. The injection as well as confinement of holes into the active region is improved in LEDC in comparison to other two LEDs. In LEDC, among all the QWs, the most prominent increase in hole concentration is observed in QW closest to p-side i.e. ~35% in comparison to LEDA. The overall hole concentration is enhanced by 13% in LEDC than the conventional structure i.e. LEDA. The observed improvement in hole concentration is attributed to the reduced effective barrier height for holes as shown in Fig. 2. So, the issue of hole confinement has been reduced in LEDC as shown in Fig.3(b).
Fig.4. The radiative recombination of all the LEDs within the active region of all the LEDs in comparison at 40 A.cm-2.
Fig.4. shows the calculated radiative recombination rates of all the LEDs. It can be seen clearly from the figure that similar radiative recombination trend, in terms of quantum wells, is shown by all the LEDs, i.e. the maximum radiative recombination of electrons with holes is carried out in last QW which is next to p-GaN layer [21, 25, 32, 33]. As discussed earlier, holes have higher effective mass and lower mobility which makes it difficult for holes to move within the active region. In comparison to the holes, lower effective mass and higher mobility of electrons allows electrons to move in the active region easily. The radiative recombination rate in QW closest to p-side of LEDC is enhanced up to ~63% as compared to LEDA. Overall, LEDC shows improved radiative recombination rate i.e. ~26% as compared to LEDA. The improved hole confinement in QWs and reduced barrier height for transportation of holes are the key factors in the enhancement of radiative recombination rate.
Fig.5. Spontaneous emission spectra of LEDA, LEDB and LEDC
Fig.5. represents the emission spectra of LEDA, LEDB and LEDC. All LEDs show peak emission spectra within the green region of visible spectrum i.e. ~ 525 nm. The broadening of full width at the half maximum (FWHM) is observed to be more in LEDC as compared to LEDA and LEDB. Besides FWHM, the peak emission spectra of LEDC is approximately doubled as compared to conventional
LED i.e. LEDA. The integrated emission spectra of LEDA, LEDB and LEDC are 4410.589 s-1eV-1, 5281.477 s-1eV-1, 7329.588 s-1eV-1 respectively. Therefore, LEDC shows maximum emission spectra as compared to LEDA and LEDB.
Fig.6. IQE (Normalized) and LOP of LEDA, LEDB and LEDC with respect to current density.
The dependence of IQE (η) and light output power (LOP) on injection current is demonstrated for all the LEDs in Fig.6. In comparison to the conventional structure i.e. LEDA, improved LOP is observed in other structures i.e. LEDB and LEDC. At 100 A/cm2, the LOP of LEDA, LEDB and LEDC is 68 mW, 83 mW and 117 mW respectively. So, in other words we can say that LOP of LEDC is enhanced up to ~42% and ~29% as compared to that of LEDA and LEDB respectively. The efficiency droop, ɳɳ
calculated as
/
ɳ
, is ~53%, ~43% and ~21% in LEDA , LEDB and LEDC respectively.
So, in our proposed structure not only the efficiency peak is increased but droop ratio is also decreased at high current density which is necessary for the enhancement of device properties. Conclusion In conclusion, InGaN-based LEDs with specially designed EBLs are investigated numerically. By inserting proposed graded EBL, better hole concentration is observed in the active region which is attributed to the decrease in valence band offset. Therefore, the suggested structure shows the overall improved radiative recombination rate, increased LOP and enhanced IQE peak as well as reduced droop ratio. To put it in a nutshell, our proposed structure is a better choice for high performance of InGaN-based green LEDs. Acknowledgements We are highly grateful to Semiconductor Photonics Laboratory, Hanyang University, South Korea for providing the needed resources.
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Dear Editor Superlattices and Microstructures
We believe that following are the highlights of our work.
1. In this work, we propose a special design of EBL layers to improve the device performance of GaN-based green light-emitting diodes. 2. Detailed comparison of optoelectronic properties of the reference and our proposed GaNbased light-emitting diodes has been presented 3. We believe that our proposed design may substantially improve the device performance, especially in the green emission range.
We look forward to your critical review and valuable reply.
Regards, Muhammad Usman, Ph.D. Ghulam Ishaq Khan Institute of Engineering Sciences & Technology Pakistan
Dear Editor
Author Statement:
Conceptualization;
Muhammad Usman, Abdur-Rehman Anwar
Data curation;
Abdur-Rehman Anwar
Formal analysis;
Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif
Funding acquisition;
N/A
Investigation; Malik, Noor Ul Islam
Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif, Shahzeb
Methodology;
Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif
Project administration;
Muhammad Usman
Resources; Jamal
Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif, Habibullah
Software;
Muhammad Usman, Abdur-Rehman Anwar,
Supervision;
Muhammad Usman
Validation; Malik, Noor Ul Islam
Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif, Shahzeb
Visualization;
Muhammad Usman, Abdur-Rehman Anwar
Roles/Writing – original draft; Muhammad Usman, Abdur-Rehman Anwar, Writing – review & editing. Muhammad Usman, Abdur-Rehman Anwar, Munaza Munsif, Habibullah Jamal, Shahzeb Malik, Noor Ul Islam
Regards, Muhammad Usman, Ph.D. Ghulam Ishaq Khan Institute of Engineering Sciences & Technology Pakistan
Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: