Semiconductor Science and Technology最新文献

{"title":"Biexcitons and quadrons in self-assembled quantum dots","authors":"Nguyen Hong Quang, Nguyen Thi Kim Thanh and Nguyen Que Huong","doi":"10.1088/1361-6641/ad3d7c","DOIUrl":"https://doi.org/10.1088/1361-6641/ad3d7c","url":null,"abstract":"We theoretically study biexcitons and quadrons in quantum dots with parabolic confinement and give a complete comparison between the two excitations. The calculation of quadron and biexciton binding energies as functions of electron-to-hole confinement potentials and mass ratios, using the unrestricted Hartree–Fock method, shows the essential differences between biexcitons and quadrons. The crossover between the negative and positive binding energies is indicated. The effect of an external magnetic field on the quadron and biexciton binding energies has also been investigated. In addition, the crossover between anti-binding and binding of both excited quadron and biexciton states in a certain range of the electron-to-hole oscillator length ratios has been found.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"30 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140805387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing external quantum efficiency of deep ultraviolet micro-leds through geometry design and multi-physics field coupling analysis","authors":"Yujie Gao, Xun Hu, Lingli Zhu, Na Gao, Rui Zhou, Yaping Wu, Kai Huang, Shuping Li, Junyong Kang, Rong Zhang","doi":"10.1088/1361-6641/ad3a93","DOIUrl":"https://doi.org/10.1088/1361-6641/ad3a93","url":null,"abstract":"High-efficiency deep-ultraviolet (DUV) micro light-emitting diodes (LEDs) are explored for inspiring development in numerous fields, such as non-line-of-sight solar-blind communication, optical pumping, and maskless lithography. In this study, we performed FDTD and SimuLED calculations to investigate the optimized DUV micro-LED structure geometry for high light extraction efficiency (LEE) by designing different mesa structures, including square, hexagonal, and circular geometries of micro-LEDs emitted at a wavelength of 275 nm. The results showed that a circular mesa of 5 <italic toggle=\"yes\">μ</italic>m diameter achieved a LEE of 27% from the bottom and sidewall emissions of as-prepared DUV micro-LED. And both the near- and far-field transverse magnetic polarized light intensities were enhanced by a factor of 1.5 over the square and hexagonal mesas. Meanwhile, the transverse electric (TE) polarized light of the circular mesa structure was enhanced and concentrated along the normal direction. Moreover, the internal quantum efficiency (IQE) of circular mesas with varied sizes was comprehensively investigated in the interactions of the thermal and electric fields. An AlGaN-based DUV micro-LED with a diameter of 5 <italic toggle=\"yes\">μ</italic>m was found to obtain the highest IQE owing to a high current-density distribution and its self-heating properties, thereby achieving a sufficiently high external quantum efficiency of 26.75%. This study provides a comprehensive technical report, including electrical, thermal, and optical analyses, and a new perspective for developing high-efficiency, high-performance DUV micro-LEDs in practical applications.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"22 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140608869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced efficiency of deep ultraviolet light-emitting diodes utilizing full-coverage Al reflector and highly reflective Ni/Rh p-electrode","authors":"Zhenxing Lv, Zhefu Liao, Shengjun Zhou","doi":"10.1088/1361-6641/ad3a92","DOIUrl":"https://doi.org/10.1088/1361-6641/ad3a92","url":null,"abstract":"Increasing the reflection of p-side is an effective way to improve the optoelectronic performance of flip-chip light-emitting diodes (FCLEDs). Here, we propose a full-coverage Al reflector (FAR) and a highly reflective Ni/Rh p-electrode to enhance the performance of deep ultraviolet (DUV) FCLEDs. The physical mechanism for the impact of the FAR and Ni/Rh electrode on the light extraction efficiency (LEE) is discussed theoretically. Simulations demonstrate that the combination of the FAR and Ni/Rh electrode improves the LEEs of transverse electric- and transverse magnetic-polarized light by 13.62% and 27.08%, respectively. At an injection current of 100 mA, the fabricated DUV FCLEDs with FAR and Ni/Rh electrode exhibits an external quantum efficiency of 4.01% and a wall plugging efficiency of 2.92%, which are 16.85% and 13.18% higher than those of conventional DUV FCLEDs, respectively. These results support the promise of the FAR and Ni/Rh electrode for high-power DUV LED applications.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"78 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140608629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance improvement of enhancement-mode GaN-based HEMT power devices by employing a vertical gate structure and composite interlayers*","authors":"Zhonghao Sun, Jianxun Dai, Huolin Huang, Nan Sun, Jiayu Zhang, Yun Lei, Dawei Li, Kaiming Ma, Huimin Yu, Yanhong Liu, Hui Huang, Yung C Liang","doi":"10.1088/1361-6641/ad31c5","DOIUrl":"https://doi.org/10.1088/1361-6641/ad31c5","url":null,"abstract":"In this work, p-n junction vertical gate (JVG) and polarization junction vertical gate (PVG) structures are for the first time proposed to improve the performance of GaN-based enhancement-mode (E-mode) high electron mobility transistor (HEMT) devices. Compared with the control group featuring the vertical gate structure, a highly improved threshold voltage (<italic toggle=\"yes\">V</italic>\u0000_th) and breakdown voltage (<italic toggle=\"yes\">BV</italic>) are achieved with the assistance of the extended depletion regions formed by inserting single or composite interlayers. The structure dimensions and physical parameters for device interlayers are optimized by TCAD simulation to adjust the spatial electric field distribution and hence improve the device off-state characteristics. The optimal JVG-HEMT device can reach a <italic toggle=\"yes\">V</italic>\u0000_th of 3.4 V, a low on-state resistance (<italic toggle=\"yes\">R</italic>\u0000_on) of 0.64 mΩ cm², and a <italic toggle=\"yes\">BV</italic> of 1245 V, while the PVG-HEMT device exhibits a <italic toggle=\"yes\">V</italic>\u0000_th of 3.7 V, an <italic toggle=\"yes\">R</italic>\u0000_on of 0.65 mΩ cm², and a <italic toggle=\"yes\">BV</italic> of 1184 V, which could be further boosted when an additional field plate design is employed. Thus, the figure-of-merit value of JVG- and PVG-HEMT devices rise to 2.4 and 2.2 GW cm⁻², respectively, much higher than that for the VG-HEMT control group (1.0 GW cm⁻²). This work provides a novel technical approach to realize higher-performance E-mode HEMTs.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"70 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electronic transport properties of WS2 using ensemble Monte Carlo method","authors":"M Derya Alyörük","doi":"10.1088/1361-6641/ad2ec6","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2ec6","url":null,"abstract":"The electronic transport characteristics of tungsten disulfide (WS₂) sheets are studied using the ensemble Monte Carlo technique in the presence of intrinsic scattering mechanisms only. The transport properties of the material are obtained in a two-valley model where intra- and inter-valley scatterings are considered in K and Q valleys. The velocity overshoot effect is observed for some applied field values. Negative differential phenomena are seen for some values of the energy difference between K and Q valleys (<inline-formula>\u0000<tex-math><?CDATA $Delta E_mathrm{KQ}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:msub><mml:mi>E</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">K</mml:mi><mml:mi mathvariant=\"normal\">Q</mml:mi></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"sstad2ec6ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>), therefore <inline-formula>\u0000<tex-math><?CDATA $Delta E_mathrm{KQ}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:msub><mml:mi>E</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">K</mml:mi><mml:mi mathvariant=\"normal\">Q</mml:mi></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"sstad2ec6ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> and the effective mass of carriers in the Q valley has a critical role in the transport and mobility characteristics of WS₂. The mobility of carriers is calculated as a function of temperature and the results are compatible with some existing theoretical and experimental predictions.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"194 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of halogen precursors on the growth of InSb nanostructures","authors":"Alexander K Sten, Kevin M Roccapriore, Brian Squires, Chris Littler, A J Syllaios, Usha Philipose","doi":"10.1088/1361-6641/ad2bac","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2bac","url":null,"abstract":"The present work highlights the role of halogen compounds in modifying the shape of the InSb nanostructures, while maintaining a high crystalline quality of the nanostructures. One-dimensional (1D) nanowires (NWs) and two-dimensional (2D) nanoplatelets (NPLs) were synthesized by ambient pressure chemical vapor deposition. Our experimental results suggest that at a critical growth temperature of 512 ^∘C, InSb NWs grow by the traditional vapor–liquid–solid growth mechanism when gold (Au) nanoparticles are used to initiate growth on an InSb film. The resulting NWs were found to have a cylindrical or tapered shape, were of high crystalline quality, and had stoichiometric composition. In the presence of halogen precursors, a change in morphology was observed and the resulting nanostructures were 2D NPLs and faceted NWs. Using existing models of crystal growth and concepts of volume, surface and edge energies, the experimental results are explained on the basis of chlorine atoms adsorbed on the wide or narrow facets of a nanocrystal, initiating nucleation and facilitating NPL or faceted NW formation. The incorporation of the chlorine atoms add a new degree of freedom to CVD synthesis of nanostructures and the results are promising for the controlled growth of novel 1D and 2D nanostructures for nano-electronic devices.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"107 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved resistive switching characteristics of solution processed ZrO2/SnO2 bilayer RRAM via oxygen vacancy differential","authors":"Kihwan Choi, James Jungho Pak","doi":"10.1088/1361-6641/ad2b07","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2b07","url":null,"abstract":"In this study, a solution-processed bilayer structure ZrO₂/SnO₂ resistive switching (RS) random access memory (RRAM) is presented for the first time. The precursors of SnO₂ and ZrO₂ are Tin(Ⅱ) acetylacetonate (Sn(AcAc)₂) and zirconium acetylacetonate (Zr(C₅H₇O₂)₄), respectively. The top electrode was deposited with Ti using an E-beam evaporator, and the bottom electrode used an indium–tin–oxide glass wafer. We created three devices: SnO₂ single-layer, ZrO₂ single-layer, and ZrO₂/SnO₂ bilayer devices, to compare RS characteristics such as the <italic toggle=\"yes\">I</italic>–<italic toggle=\"yes\">V</italic> curve and endurance properties. The SnO₂ and ZrO₂ single-layer devices showed on/off ratios of approximately 2 and 51, respectively, along with endurance switching cycles exceeding 50 and 100 DC cycles. The bilayer device attained stable RS characteristics over 120 DC endurance switching cycles and increased on/off ratio ∼2.97 × 10². Additionally, the ZrO₂/SnO₂ bilayer bipolar switching mechanism was explained by considering the Gibbs free energy (Δ<italic toggle=\"yes\">G</italic>\u0000^o) difference in the ZrO₂ and SnO₂ layers, where the formation and rupture of conductive filaments were caused by oxygen vacancies. The disparity in the concentration of oxygen vacancies, as indicated by the Gibbs free energy difference between ZrO₂ (Δ<italic toggle=\"yes\">G</italic>\u0000^o = −1100 kJ mol⁻¹) and SnO₂ (Δ<italic toggle=\"yes\">G</italic>\u0000^o = −842.91 kJ mol⁻¹) implied that ZrO₂ exhibited a higher abundance of oxygen vacancies compared to SnO₂, resulting in improved endurance and on/off ratio. X-ray photoelectron spectroscopy analyzed oxygen vacancies in ZrO₂ and SnO₂ thin films. The resistance switching characteristics were improved due to the bilayer structure, which combines a higher oxygen vacancy concentration in one layer with a lower oxygen vacancy concentration in the switching layer. This configuration reduces the escape of oxygen vacancies to the electrode during RS.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"21 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insights into dynamic switching behavior and electric field distribution of depletion-mode GaN HEMT with bonding pad over active layout","authors":"Lijian Guo, Feng Zhou, Weizong Xu, Fangfang Ren, Dong Zhou, Dunjun Chen, Rong Zhang, Youdou Zheng, Hai Lu","doi":"10.1088/1361-6641/ad2a7f","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2a7f","url":null,"abstract":"Bonding pad over active (BPOA) layout, which stacks traditional horizontal structure pad electrodes vertically above the active area, is an area-effective device architecture and packaging-enabled solution for GaN-based high electron mobility transistors (HEMTs). In this work, the dynamic switching and electric field distribution of such layout, as well as associated capacitance–voltage and trapping characteristics, are comprehensively studied on D-mode GaN-on-sapphire HEMT by performing numerical simulations. In terms of different pad electrodes covering the active area, BPOA is composed of various structures such as gate-related and drain-related BPOAs (i.e. G-BPOA and D-BPOA), among which G-BPOA exhibits inferior switching characteristics due to the additional introduction of Miller capacitance that prolongs the device switching, while breakdown voltage of D-BPOA is 400–900 V lower than other BPOA counterparts due to the interplay between D-BPOA and the drain electrode. Furthermore, the effects of trap capture cross section and trap density on switching characteristics are evaluated. These results highlight the differences in electrical characteristics of various structures within the BPOA layout, and provide valuable insights into BPOA device design and performance improvement.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"72 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Over 43%-power-efficiency GaInN-based photoelectric transducer on free-standing GaN substrate for optical wireless power transmission system","authors":"Takahiro Fujisawa, Nan Hu, Tomoki Kojima, Takashi Egawa, Makoto Miyoshi","doi":"10.1088/1361-6641/ad2d62","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2d62","url":null,"abstract":"We investigated the GaInN-based photoelectric transducers (PTs) aiming at the application to optical wireless power transmission systems. A PT device structure with Ga_0.9In_0.1N multiple-quantum-wells (MQWs) as a light absorption layer was grown on a free-standing GaN substrate by metalorganic chemical vapor deposition and subjected to the device fabrication. The PT performance was evaluated via the two-terminal current-density vs. voltage characteristics taken under a monochromatic light illumination. The fabricated PT devices exhibited a high open-circuit voltage of approximately 2.3 V and a high shunt resistance of 41 kΩcm², thanks to its good material qualities. In addition, its surface reflection was markedly suppressed by an adoption of a wet surface treatment and an anti-reflection coating, resulting in a high external quantum efficiency of 90% and a high short-circuit current density of 1.4 mAcm⁻². Through the above investigation, a high power-conversion efficiency as great as 43.7% was achieved for the GaInN MQW PTs at a light illumination with 390 nm in wavelength and 5 mWcm⁻² in optical power density.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"49 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on low-temperature evaporation of Ag2O-based Ag electrode and electron injection layer and their application in OLEDs","authors":"Yachen Xu, Jialu Gu, Lulu Zhou, Bingjia Zhao, Yangyang Zhu, Wei Shi, Bin Wei","doi":"10.1088/1361-6641/ad2d63","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2d63","url":null,"abstract":"Organic light-emitting diodes (OLEDs) have become one of the mainstream lighting and display technologies. The vacuum thermal evaporation is the most widely adopted method for the preparation of organic and metal materials of OLEDs. The thermal deposition of the commonly used silver (Ag) and aluminum (Al) electrodes requires high temperature and long time, which greatly increases the cost of the fabricating process. Therefore, we selected silver oxide (Ag₂O) powder instead of Ag pellets as the precursor for evaporating Ag electrodes. Compared to Ag pellets and Al wires, Ag₂O-based Ag electrode need lower evaporation temperature and shorter preheating time. In addition, the agglomeration phenomenon on the surface of the Ag₂O-based Ag film is prevented, which also increases the carrier concentration of Ag electrode. Moreover, by doping bathophenanthroline (Bphen) in Ag₂O powders, the phenanthroline-metal (Bphen-Ag) complexes with higher electron mobility and stronger electron injecting ability can be achieved. We applied Ag₂O-based Ag electrode and 10 wt.% Ag₂O-based Ag:Bphen as electron injection layer to achieve high-efficiency red phosphorescent inverted OLEDs, with the maximum current efficiency, external quantum efficiency, and power efficiency of 17.79 cd A⁻¹, 20.71%, and 12.14 lm W⁻¹, respectively. This method provides a new strategy for preparing highly efficient inverted red OLED devices.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"53 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}