Nowadays, the importance of Atmospheric windows in optoelectronic industries is not hidden from anyone. On the other hand, using graphene nanoribbons widely has been applied in optical devices. So, ...armchair graphene nanoribbons (AGNRs) from three different families as IR photodetectors are proposed and modeled, in this work. Our results show that the energy gap of AGNRs has been in the 1–3 μm and 8–14 μm atmospheric windows in the pure state and with nitrogen (N)/boron (B) substitutional doping. Also, responsivity and specific detectivity (D*) have been calculated, by introducing a simple structure as an IR photodetector. The energy gap and dark current (Jdark) calculations have been done by density functional theory (DFT) and non-equilibrium Green's function (NEGF) formalism, respectively. The specific detectivity peaks on the order of 109 cmHz1/2/W for 9-AGNR and 10-AGNR at 1–3 μm atmospheric window have been concluded. Furthermore, our results show that 11-AGNR with B dopants can be used to design dual-band detectors in the 1–3 μm and 8–14 μm atmospheric windows.
•An IR photodetector based on three N-AGNRs is introduced.•The value of the band gap of AGNRs in the pure states and the presence of impurities have been reported.•The energy gap and dark current (Jdark) calculations have been done by DFT and NEGF formalism, respectively.•The D* peaks on the order of 109 cmHz1/2/W for 9-AGNR and 10-AGNR at 1–3 μm have been concluded.•The results show that 11-AGNR with B dopants can be used to design dual-band detectors in the 1–3 μm and 8–14 μm windows.
Using the first-principle calculations, we study the electronic band structure, density of state (DOS), effective mass, quantum capacitance, transmission spectrum, and current–voltage characteristic ...of armchair silicene nanoribbons (ASiNRs) doped with aluminum (Al) and phosphorus (P) atoms. ASiNR is an intrinsic semiconductor, and depending on the type of impurity atoms applied, it becomes an n-type and p-type semiconductor. Our numerical results show several open energy windows and different peaks in the transmission spectra under various applied bias. These effects cause nonlinear behavior in the current–voltage curves. Also, the value of current density for four samples is obtained as Jpure>JAl>JP>JAl&P at a fixed voltage. The threshold voltage for these samples are given as Vpureth>VAlth>VPth>VAl&Pth. The effective masses of carriers increase in the pure and doped ASiNR systems are calculated from the band structures spectra. Moreover, the quantum capacitance of the pure and doped ASiNR is investigated for direct and reverse biases. The results of this work may be useful in novel phenomena such as nanoelectronics applications and near-infrared photodetectors.
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•Electrical transport properties of four ASiNR junctions have been studied in the presence of Al and P atoms.•Our calculations are based on DFT as implemented in SIESTA package.•The doped ASiNRs show several energy gaps due to mid-gap states, which is absent in the pure system.•The results may be useful in near-infrared photodetectors.•At low bias, a rectifying effect is observed in the devices, which the threshold voltages depend on the type of doping.
•The dependency of the low field electron mobilities of Hg1-xCdxTe to doping and temperature are studied.•The Boltzmann transport equation (BTE) is solved by modified iterative method.•The mobility ...of In-doped and annealed n-type Hg1-xCdxTe samples are examined by Hall measurement.•The effect of annealing at 150K on the mobility enhancement of Hg0.78Cd0.22Te samples was shown better than Hg0.7Cd0.3Te.•Theoretical and experimental results have shown a good agreement.
The dependency of the low field electron mobilities of Hg0.78Cd0.22Te and Hg0.7Cd0.3Te structures to doping and temperature are calculated by using the iterative method in the thermal range of 75−300 K. we have examined the mobility of In-doped and annealed samples of Hg0.78Cd0.22Te and Hg0.7Cd0.3Te structures. The effect of annealing in the atmospheric pressure of Hg at 150 K and for 10 h on the mobility of Hg0.78Cd0.22Te was better than Hg0.7Cd0.3Te. In order to validate the computational results, we have compared them with the measured mobility results. Observed discrepancies between theoretical and experimental data was obtained 3% and 5% for x = 0.22 and 0.3 respectively at temperature 300 K. It indicated that the iterative method for low compensated Hg0.78Cd0.22Te and Hg0.7Cd0.3Te can be an applicable model for mobility estimation especially for temperatures above 150 K.
Recently, bio-solar cells have garnered significant attention owing to their relatively high efficiency and cost-effectiveness, positioning them as alternative devices for solar energy harvesting. ...This study delves into the optical and electrical transport characteristics of a novel bilayer bio-solar cell using the total system transfer matrix method, theoretically. These bilayer bio-solar cells consist of two distinct layers of Chlorophyll-a and Chlorophyll-b, forming a heterojunction in the bio-solar cell architecture. Within these solar cells, photon absorption by the active layers of chlorophyll generates excitons and quasi-particles (bound electron and hole pairs), which subsequently diffuse through the collecting layer, resulting in significant recombination losses. The influence of the thickness of chlorophyll adsorbent active layers on the short circuit current density and quantum efficiency is examined through numerical calculations. Furthermore, we develop models for the solar cell parameters of thin film heterojunction photovoltaic devices based on Chlorophyll-a/Chlorophyll-b. The results indicate efficient short circuit current and quantum efficiency values (or power conversion efficiency) of 72 A/m2 and 3.30 %, respectively. It is demonstrated that optimizing the thickness of bio-solar cells based on these findings may enhance electron transport, leading to higher photocurrents and improved overall efficiency. These simulation outcomes pave the way for optimizing the thickness of bio-solar cells and advancing towards higher efficiencies.
In recent years, the construction of lateral heterostructures of two-dimensional (2D) monolayers of transition metal dichalcogenides (TMDC) has been attracting considerable interest due to its ...numerous applications in electronic and optoelectronic devices. In this work, the optical absorption coefficient of the Lateral Single Quantum Well (LSQW) based on
MoS
2
/
WSe
2
is analyzed theoretically. For this purpose, we rederive the absorption coefficient equation for LSQW and investigate the parameters affecting the absorption coefficient of LSQW such as the type of polarization and incident angle as well as spin–orbit coupling (SOC). Our results show the significant effect of the spin–orbit effect on the maximum value of the absorption coefficient so that by including the SOC, the values of absorption coefficient increases. We surprisingly found that increasing the well width enhances the optical absorption in LSQW. Our findings and predictions might be implemented in new emerged optovalleytronic devices.
Graphical abstract
(
a
) Absorption coefficient as a function of the photon energy with various incident angle. (
b
) Absorption coefficient as a function of the incident angle.
Thermoelectric materials include an extensive spectrum of solid-state compounds capable of converting thermal and electricity energies into each other. Due to their little harm to nature and their ...potential for fuel consumption reduction purposes, the thermoelectric materials have drawn great attentions in recent years. In this study, first-principle density functional theory (DFT) in conjunction with semi-classic Boltzmann transport theory is used to investigate the thermoelectric properties of Zirconium Nitride (ZrN) alloyed with different amounts of Magnesium. In order to show that the MgxZr1−xN alloy can act as a thermoelectric material its Seebeck coefficient, electrical conductivity, thermal conductivity, Hall coefficient, and thermoelectric power factor are studied. The Seebeck coefficient and electrical conductivity in the considered chemical potential and temperatures ranges have shown high values. In addition, it is found out that electronic contribution of thermal conductivity is one order of magnitude less in comparison with the other good thermoelectric materials.
•We did our calculations using DFT and Boltzmann’s semi-classical theory.•Band structure results showed, x = 0.375 and 0.5 values of Mg are semiconductors.•Seebeck coefficient Values indicate potential candidate of thermoelectric material.•TPF of x = 0.125, 0.25, and 0.375 are competitive with thermoelectric materials.
In electron curtain accelerator, the absorbed dose and its uniformity, electron energy loss through beam extract window and its lifetime are key factors for users. To facilitate design and ...application of curtain electron accelerator in 100–300 keV energy range, with the typical electron beam current (43 mA) and 13-µm-thick extract titanium window, the amount of doses immediately after the extract window, on the target position and at the depth of 1 mm of the target was obtained by MCNP4C code. The results of this simulation showed that with increasing energy, dose increases at indicated positions. It is shown that, by increase the incident beam energy from 100 keV to 300 keV, the temperature on the titanium extract window decreased from 104 to 42 degrees centigrade, respectively. Furthermore, lateral dose distribution and beam energy loss through the typical extract window was obtained based on CASINO numerical simulation package and compared with analytical results.
•In electron curtain accelerator, the absorbed dose and its uniformity are key factors.•Electron Beam (EB) dosimetry was performed for energies of 100–300 keV using the MCNP4C.•The effect of extract window on energetic electron behavior was investigated.•The temperature rise was calculated based on the results of the deposited energy in the extract windows.
By first-principles calculations, we study quantum electrical transport properties of four nanojunctions based on armchair graphene nanoribbons (AGNRs) in the presence of nitrogen (N) and boron (B) ...atoms. The theoretical calculations perform within the non-equilibrium Green’s function (NEGF) method combined with density functional theory (DFT). The numerical results show distinct properties, such as converting the system into n-type and p-type semiconductors with several energy gaps due to mid-gap states. These characteristics may be useful in near-infrared photodetectors. By referring to the band structures spectra, we perceive that the effective mass of carriers increases in the doped AGNR systems. Moreover, we calculate the current–voltage characteristic and quantum capacitance of four AGNR nanodevices, theoretically. According to our results, a rectifying effect is observed at low bias voltage, while the threshold voltages depend on the type of doping.
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•Electrical transport properties of four AGNR nanojunctions have been studied in the presence of N and B atoms.•Our calculations are based on DFT as implemented in SIESTA package.•An n-type and p-type AGNRs with several energy gaps due to mid-gap states be produced by the substitutional dopings.•These results may be useful in near-infrared photodetectors.•A rectifying effect is observed at low bias voltage in the devices, which the threshold voltages depends on the type of doping.
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