Epitaxial growth and characterization of III-V group solar cell structures

Bu çalışmada, III-V grubu GaAs/Ge, GaxIn1-xP/GaAs iki eklemli ve GaxIn1-xP/GaAs/Ge üç eklemli güneş hücrelerinin epitaksiyel yapı tasarımları yapıldı ve bu yapılardan aygıt uygulamaları için uygun olanlar MBE tekniği büyütüldü. Öncelikle üç eklemli hücrenin birinci eklemini oluşturan p?-n eklem Ge hücresinin kalibrasyon çalışmaları yapıldı. Bu amaçla 5 adet p-Ge alttaş üzerine As tabakalarının birikimi farklı alttaş ve tavlama sıcaklığında göç yoluyla büyütme ?migration enhanced epitaxy? ile sağlandı ve burada bir p-n eklem yapı elde edildi. Ge hücre kalibrasyonu tamamlandıktan sonra, p-n eklem Ge hücresi üzerine ikinci hücre olan p-n eklem GaAs hücresi büyütülerek iki eklemli GaAs/Ge güneş hücre yapısı elde edildi ve karakterizasyonları yapıldı. Daha sonra alaşım oranı kalibrasyonu için farklı x oranına sahip 3 adet GaxIn1-xP üçlü alaşımı GaAs alttaşlar üzerine ayrı ayrı büyütüldü ve yapıların karakterizasyonları yapıldı. GaxIn1-xP yapısnın kalibrasyon çalışmalarından sonra GaxIn1-xP/GaAs iki eklemli güneş hücre yapısı büyütüldü ve karakterizasyonları yapıldı. Son olarak, GaxIn1-xP/GaAs/Ge üç eklemli güneş hücre yapısının büyütülmesi ve karakterizasyonlarının yapılması ile çalışma tamamlandı. Yapısal, optik, morfolojik ve elektriksel karakterizasyonlar için HR-XRD, SIMS, PL, AFM, SE ve HMS ölçüm sistemleri kullanıldı.In this study, the epitaxial structure of III-V compound double junction GaxIn1-xP/GaAs and triple junction GaxIn1-xP/GaAs/Ge solar cells was designed and the suitable structures for device application were grown using MBE technique. Firstly, the first junction of the triple junction cell, p-n junction Ge cell, was calibrated and grown. The deposition of As layers on five pieces of Ge substrate was carried out at different substrate and annealing temperatures by migration enhanced epitaxy (MEE) and the p-n junction was formed. After the completion of Ge cell calibration, the second cell, p-n junction GaAs cell, was grown on Ge cell and the characterization of GaAs/Ge double junction solar cell was done. Then, three GaxIn1-xP ternary alloys with different composition were separately grown on GaAs substrates and characterized for the calibration of alloy ratio. After the calibration of GaxIn1-xP structure, double junction GaxIn1-xP/GaAs cell was grown and characterized. Finally, this study is completed by growing and characterizing triple junction GaxIn1-xP/GaAs/Ge cell. For the structural, electrical and optical characterization of the structures, HR-XRD, SIMS, PL, AFM, SE and HMS systems were used

The temperature dependent negative dielectric constant phenomena of Au/n–GaAs structure with CZO interfacial layer

In this study, the copper-doped (wt 3%) ZnO (CZO) thin film was deposited on n–type (100)–oriented GaAs substrate with the RF sputtering system and this film was annealed at 600°C. The dielectric parameters such as dielectric con- stant (e0), dielectric loss (e00), dielectric loss tangent (tand), real (M0) and the imaginary (M00) part of the electric modulus, and ac conductivity (rac) of Au/n– GaAs MOS structure with CZO thin film were examined in the temperature range of 200–380 K by 30 K steps. The variations of these parameters depending on the voltage were also discussed in the range of 1.5 V to 3.0 V by step 0.5 V. Dielectric constant has been studied in detail in three different temperature ranges as low (200 – 260 K), medium (290 K), and high (300 – 380 K). While the dielectric constant takes positive values for the low and medium temperature range in the forward bias voltage region, it takes negative values for the high temperature region. As a result of this study, negative dielectric constant behavior was observed for high temperature values

Functional optical design of thickness-optimized transparent conductive dielectric-metal-dielectric plasmonic structure

Dielectric/metal/dielectric plasmonic transparent structures play an important role in tailoring the high-optical performance of various optoelectronic devices. Though these structures are in significant demand in applications, including modification of the optical properties, average visible transmittance (AVT) and colour render index (CRI) and correlated colour temperature (CCT), obtaining optimal ones require precise thickness optimization. The overall objective of this study is the estimation of the optimal design concept of MoO3/Ag/WO3 (10/d(Ag)/d(WO3) nm) plasmonic structure. To explore the proper use in optoelectronic devices, we are motivated to conduct a rigorous optical evaluation on the thickness of layers. Having calculated optical characteristics and achieved the highest AVT of 97.3% for d(Ag) = 4 nm and d(WO3) = 6 nm by the transfer matrix method, it is quite possible to offer the potential of the structure acting as a transparent contact. Notably, the colour coordinates of the structure are x = 0.3110 and y = 0.3271, namely, it attributes very close to the Planckian locus. This superior colour performance displays that MoO3/Ag/WO3 shall undergo rapid development in neutral-colour windows and LED technologies. Structure with d(Ag) = 6 nm and d(WO3) = 16 nm exhibits the highest CRI of 98.58, thus identifying an optimal structure that can be integrated into LED lighting applications and imaging technologies. Besides the colour of structure with d(Ag) = 4 nm and d(WO3) = 8 nm is equal for D65 Standard Illuminant, the study reports that the range of CCTs are between 5000 and 6500 K. This optimization makes the structure employable as a near-daylight broadband illuminant. The study emphasizes that optimal MoO3/Ag/WO3 plasmonic structures can be used effectively to boost optoelectronic devices' performance

In-depth analysis on PTB7 based semi-transparent solar cell employing MoO3/Ag/WO3 contact for advanced optical performance and light utilization

Abstract Novel semi-transparent organic solar cells (ST-OSC) can be designed with high average visible transmittance (AVT) while at the same time exhibiting superior photovoltaic performance. This reach requires their design to be based not only on conventional window applications but also on functional industrial applications that require exceptional optical performance. In ST-OSC, high AVT can be achieved by photonic-based dielectric/metal/dielectric (DMD) transparent contact engineering. Functional optical modification can also be made with a fine-tuned design of DMD that includes a light management engineering-based approach. Thus, ST-OSCs can be suitable for aesthetic, colourful and decorative industrial windows that provide natural lighting. In this study, we determined optimal ST-OSCs based on a novel PTB7:PC71BM polymer blend with MoO3/Ag/WO3 asymmetric DMD top contact by examining extraordinary optical properties such as AVT, colour rendering index, correlated colour temperature and colour perception over 10 thousand designs. In addition to determining the optimality and extraordinary optical limits for PTB7, we also evaluated the photon-harvesting and photovoltaic performance of ST-OSCs from external quantum efficiency and quantum utilization efficiency. In optimal situations, ST-OSCs offering 48.75% AVT, 99.08 CRI, and sky-blue colours were designed and determined to generate short-circuit current densities of 9.88 mA·cm−2, 13.64 mA·cm−2, and 13.06 mA·cm−2, respectively

Enhancement of color and photovoltaic performance of semi-transparent organic solar cell via fine-tuned 1D photonic crystal

Semi-transparent organic solar cells’ (ST-OSCs) photovoltaic and high optical performance parameters are evaluated in innovative applications such as power-generating windows for buildings, automobiles, and aesthetic designs in architectural and industrial products. These parameters require the precision design of structures that optimize optical properties in the visible region and aim to achieve the required photon harvest in UV and IR. These designs can be realized by integrating wavelength-selective photonics-based systems into ST-OSC to increase localized absorption in wavelengths greater than 600 nm and NIR and provide modifiable optical properties. In this study, methodologically, we followed highly detailed light management engineering and transfer matrix method-based theoretical and experimental approaches. We discussed the optimal structures by evaluating color, color rendering index, correlated color temperature, and photovoltaic performances for ST-OSCs, including one-dimensional photonic crystal (1D-PC) designed at different resonance wavelengths (λB) and periods. Finally, by integrating fine-tuned (MgF2/MoO3)N 1D-PC, we report the inherently dark purple-red color of the P3HT:PCBM bulk-heterojunction-based ST-OSC neutralizes with the optimal state was 0.3248 and 0.3733 by adjusting close to the Planckian locus. We also enhanced short current density from 5.77 mA/cm2 to 6.12 mA/cm2 and PCE were increased by 7.34% from 1.77% to 1.90% designed for the N = 4 period and λB = 700 nm

Negative capacitance phenomena in Au/SrTiO3/p-Si heterojunction structure

In this study, temperature- and frequency-dependent capacitance and conductance measurements of the Au/SrTiO3/p-Si heterojunction structure were examined. Strontium titanate (SrTiO3) thin films were deposited on cleaned p-type (100)-oriented silicon substrates using radio frequency (RF) magnetron sputtering method at a substrate temperature of 500 degrees C. The temperature-dependent reverse and forward bias C-V and G/omega-V characteristics of the Au/SrTiO3/p-Si heterojunction structure was realized in the temperature range of 110-350 K (by step 30 K) at 1 MHz. The frequency-dependent reverse and forward bias C-V and G/omega-V characteristics of the Au/SrTiO3/p-Si heterojunction structure was realized in the frequency range of 100-900 kHz (by step 100 kHz) at room temperature. It has been demonstrated that Au/SrTiO3/p-Si heterojunction structure exhibits negative capacitance (NC) behavior as a result of both temperature- and frequency-dependent capacitance measurements due to the reduction of interface charges, ionization states and series resistance in the forward bias voltage. In addition, it was shown that it exhibits an intersection point in the forward bias voltage of both temperature and frequency-dependent capacitance measurements. In temperature and frequency-dependent admittance spectroscopy measurements of Au/SrTiO3/p-Si heterojunction structure was observed NC phenomenon

Evaluation of dielectric properties of Au/TZO/n–Si structure depending on frequency and voltage

© 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.This study examined the dielectric properties of the titanium doped ZnO (TZO) thin film. The TZO thin film was deposited on the n-type Si substrate with the RF sputtering system and the metallization process was completed for electrical characterization. The dielectric parameters such as dielectric constant (ε′), dielectric loss (ε″) dielectric loss tangent (tan δ), and ac conductivity (σac) of the Au/TZO/n–Si structure were determined using capacitance (C) and conductance (G) data, obtained from the admittance measurements for 0.3, 0.5 and 1 MHz frequency values at room temperature. According to the experimental results, ε′–V and ε″–V curves were indicated an inductive behavior at 1 MHz. In addition, the variation of these dielectric parameters depending on the frequency in specific negative voltage and positive voltage regions were investigated. Experimental results showed that the dielectric parameters of the Au/TZO/n–Si structure are highly frequency dependent