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Structural and electrical properties of Pd/p-GaN contacts for GaN-based laser diodes
摘要： In this paper, the properties of Pd-based p-contacts on GaN-based laser diodes are discussed. Pd is often the metal of choice for ohmic contacts on p-GaN. However, for Pd/p-GaN ohmic contacts, nanovoids observed at the metal/semiconductor interface can have a negative impact on reliability and also reproducibility. The authors present a thorough analysis of the microstructure of the Pd/p-GaN interface by x-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM). STEM data show that the microvoids at the p-GaN/Pd interface form during rapid thermal annealing. A combination of the following effects is suggested to support the void formation: (1) the differences in thermal expansion coefficients of the materials; (2) excess matrix or impurity atoms in the semiconductor, at the interface, and in the metals, which are released as gases; and (3) the strong antisurfactant effect of Pd on Ga-rich p-GaN surfaces. A slow temperature ramp during contact annealing reduces the formation of voids likely by suppressing the accumulation of gases at the interface. XPS data show that the Ga/N ratio can be reduced by suitable cleaning of the p-GaN surface, which enhances Pd adhesion. As a result, the quality of the contact system is improved by the systematic optimization of the surface cleanliness as well as the annealing parameters, leading to void-free and clean Pd/p-GaN interfaces. The specific contact resistance, extracted from linear transmission line method measurements, is reduced by an order of magnitude to 2 × 10?3 Ω cm2 at 1 mA for the same epitaxial layer stack.
关键词： Pd/p-GaN contacts,STEM,nanovoids,ohmic contacts,rapid thermal annealing,XPS,GaN-based laser diodes
更新于2025-09-23 15:21:01
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1200nma??Band InAs/GaAs Quantum Dot Intermixing by Dry Etching and Ion Implantation
摘要： In this paper, the quantum dot intermixing (QDI) technique previously developed for 1550nm-band InAs/InAlGaAs quantum dot (QD) was applied to 1200nm-band InAs/GaAs QD. Three methods of defect introduction for triggering the QDI were employed such as ICP-RIE (Ar+) and ion implantation (Ar+ and B+). As a result, about 80nm PL peak wavelength shift was obtained for ICP-RIE when annealing was performed at 575 °C, after etching down to 450 nm to the QD layer. On the other hand, about 110nm PL peak wavelength shift was obtained for B+ ion implantation at an acceleration energy of 120 keV and a dose of 1.0×1014 /cm2 and subsequent annealing. Cross sectional image analyses by Scanning Transmission Electron Microscope (STEM) and Energy-Dispersive X-ray Spectroscopy (EDX) clarified the modification of InAs QD structures by the QDI process.
关键词： intermixing,InAs/GaAs quantum dot,ICP-RIE,rapid thermal annealing,ion implantation
更新于2025-09-23 15:19:57
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Boron-doped graphene synthesis by pulsed laser co-deposition of carbon and boron
摘要： Incorporating dopants, such as boron, in graphene, is crucial for many applications in electrochemistry, sensors, photovoltaics, and catalysis. Many routes have been investigated for the preparation of B-doped graphene (BG) films, including chemical processes. A different way to obtain boron-doped layers to better control the concentration of boron in the doped graphene film, is pulsed laser co-ablation of C and B solid sources followed by rapid thermal heating of the B-doped carbon film deposited on a metal catalyst. Amorphous a-C:B films, containing 2%at. boron, are synthetized by pulse laser deposition onto a nickel film catalyst. Rapid thermal annealing at 1100°C leads to the formation of boron-doped graphene films, characterized by Raman, XPS, FEG-SEM, HRTEM and AFM. The results confirm the production of 1-4 layer boron doped graphene films, with a similar 2 at.% boron concentration to that of the a-C:B used as the graphene solid precursor. Boron doping does not modify the nano-architecture of graphene, but increases the concentration of defects in the films. Our results pave a new way for boron doped graphene synthesis using laser processing in a controlled and reproducible way, in particular to achieve designed electrical and chemical properties in various electronic and electrochemical applications.
关键词： Raman spectroscopy,Boron-doped graphene,Pulsed laser deposition,Rapid thermal annealing,HRTEM,XPS,AFM
更新于2025-09-23 15:19:57
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Maximize CdTe solar cell performance through copper activation engineering
摘要： The incorporation of copper (Cu) is one of the critical processes for fabricating high-efficiency CdTe thin-film solar cells. However, due to its high mobility in CdTe, the distribution and concentration of Cu must be carefully engineered to reduce the compensative donor-like interstitial defects in CdTe bulk and the recombination centers at the buffer layer/CdTe interface to maximize device performances. Here, a cuprous chloride (CuCl) solution treatment and a rapid thermal annealing (RTA) process are used to control the concentration and distribution of Cu in CdTe absorbers, enabling a champion CdTe thin-film solar cell with a power conversion efficiency of 17.5% without selenium incorporation. The results demonstrate that the use of a CuCl solution can substantially reduce the amount of Cu needed in CdTe and the RTA process is a viable approach to engineer the Cu distribution in CdTe solar cells.
关键词： Power conversion efficiency,Rapid thermal annealing,Cuprous chloride,CdTe solar cells,Copper activation
更新于2025-09-23 15:19:57
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Controlling In‐Ga‐Zn‐O Thin‐Film Resistance by Vacuum Rapid Thermal Annealing and Application to Transparent Electrode
摘要： This study reveals that an amorphous indium gallium zinc oxide film shows a large resistance change under vacuum rapid thermal annealing, whereas a zinc tin oxide film shows little resistance change under the same treatment. Based on these findings, the applicability of amorphous indium gallium zinc oxide thin films to a transparent source/drain electrode in zinc tin oxide thin-film transistors is investigated. The optical transmittance of the amorphous indium gallium zinc oxide and amorphous zinc tin oxide films in the visible region is greater than 85%. Furthermore, a zinc tin oxide thin-film transistor with an amorphous indium gallium zinc oxide source/drain electrode exhibits superior operation characteristics than devices with indium tin oxide source/drain electrodes, such as a lower threshold swing (from 369.96 to 315.45 mV dec?1), higher mobility (from 28.47 to 36.187 cm2 V?1 s?1), and higher on/off current ratio (from 1.25 × 107 to 3.56 × 107). In addition, in positive and negative bias temperature stress tests, the zinc tin oxide thin-film transistor with an amorphous indium gallium zinc oxide source/drain electrode shows almost equal stability compared to the zinc tin oxide thin-film transistor with an indium tin oxide source/drain electrode.
关键词： Zn-Sn-O (ZTO),In-Ga-Zn-O (IGZO) S/D electrode,thin-film transistors (TFT),vacuum rapid thermal annealing
更新于2025-09-23 15:19:57
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Rapid fabrication of perovskite solar cells through intense pulse light annealing of SnO2 and triple cation perovskite thin films
摘要： Rapid evolution of perovskite solar cells (PSCs) performance and stability has inclined the research focus towards scalable bulk fabrication through high speed and cost-effective automated methods. For the first time, intense pulsed light (IPL) is utilized to rapidly fabricate efficient PSCs through swift annealing of both the SnO2 electron transport layer (ETL) and mixed triple cation perovskite thin films. The addition of di-iodomethane (CH2I2) alkyl-halide could enhance the PSC efficiency by retarding the crystallization and improving the surface morphology of the perovskite photoactive film through supplying iodine cleaved by ultraviolet energy during IPL process. The maximum efficiency and fill factor of the PSCs fabricated by IPL annealing were 12.56% and 78.3% for the rigid glass-FTO slides, and 7.6% and 64.75% for flexible PET-ITO substrates when processed in the ambient with relative humidity of 60%, respectively. The annealed materials were characterized through Scanning electron microscopy (SEM), UV-vis, photoluminescence (PL), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. In addition, impedance spectroscopy (IS) and current-voltage measurements were conducted to study the functionality of fabricated cells. Our results delineated the feasibility of sequential step IPL annealing on rapid fabrication of efficient PSCs which is directly applicable for scalable roll-to-roll manufacturing.
关键词： Di-iodomethane,SnO2,Rapid thermal annealing,Intense pulse light,Perovskite solar cell
更新于2025-09-16 10:30:52
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Theoretical correlation and effect of annealing on the photoresponse of vertically strain-coupled In <sub/>0.5</sub> Ga <sub/>0.5</sub> As/GaAs quantum dot heterostructures
摘要： Here, we propose a di?erent approach for growing strain-coupled In0.5Ga0.5As quantum dot infrared photodetectors (QDIPs) with varying dot layer periodicity. Strain calculation is done throughout the quantum dot (QD) heterostructures, which has a signi?cant e?ect on the carrier probability density functions. The localization of the electron probability density function in each heterostructure has a strong correlation with the photoresponse. The con?ned electron wavefunction in the top QD layer of the optimized device heterostructure (trilayer QDIP having dot layer periodicity of three) would be useful for hyperspectral imaging applications owing to its narrow (8.67 meV) photoresponse. Rapid thermal annealing treatment was carried out on the trilayer QDIP to investigate the enhancement in its optoelectronic properties. The dark current density reduced by two orders, and the operating temperature increased by 30 °C for the 650 °C-annealed counterpart. Also, the responsivity enhanced by two times (2.05 A/W at ?1 V) for the annealed QDIP.
关键词： In0.5Ga0.5As,rapid thermal annealing,photoresponse,strain-coupled,quantum dot infrared photodetectors
更新于2025-09-12 10:27:22
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Regional Band‐Gap Tailoring of 1550nm‐band InAs Quantum Dot Intermixing by Controlling Ion Implantation Depth
摘要： The regional control of the band-gap energies using the highly-stacked quantum dot (QD) on InP (311)B substrate changing ion implantation depths in the process of the quantum dot intermixing (QDI) technique is investigated. The QDI process involves B+ implantation and rapid thermal annealing (RTA) around 600 °C, in which the ion implantation depths are controlled regionally with a combination of SiO2 and polymer (AZ) films. Controlled blue shifts of the photoluminescence (PL) spectra verify the effectiveness of the regionally controlled QDI process for application to semiconductor photonic integrated circuits using 1550nm-band QD such as integrated WDM light sources.
关键词： rapid thermal annealing,intermixing,ion implantation,quantum dot
更新于2025-09-11 14:15:04
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The effects of rapid thermal annealing and microwave annealing on the electrical properties of ZrO2 metal-insulator-metal capacitors
摘要： The effects of different rapid thermal annealing (RTA) and microwave annealing (MWA) on the electrical behaviors of ZrO2 metal-insulator-metal (MIM) capacitors were studied in detail. The maximum capacitance density was achieved at 1400 W for MWA, i.e. ~29.29 fF/μm2 increased by ~40% compared with that of the un-annealed capacitors. For the capacitors under RTA at 370 oC, equivalent to the ambient of the MWA at 1400 W, the capacitance density is ~28.04 fF/μm2. Moreover, the leakage current density of ZrO2 MIM capacitors for MWA at 1400 W and RTA at 370 oC are determined to be about 3.55×10-7 A/cm2 and 1.88×10-6 A/cm2 at the applied voltage of -1.5 V, respectively. Finally, the possible mechanisms of the improved electrical properties of ZrO2 MIM capacitors through MWA were proposed.
关键词： ZrO2,Rapid thermal annealing,Metal-insulator-metal Capacitors,Microwave annealing
更新于2025-09-10 09:29:36
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VO <i> <sub/>n</sub></i> Complexes in RTA Treated Czochralski Silicon Wafers Investigated by FTIR Spectroscopy
摘要： Oxygen-vacancy complexes formed after rapid thermal annealing in silicon wafers were investigated by FTIR spectroscopy at 6 K. It was found that VO4 is the only detectable complex. The concentration of VO4 complexes increases with increasing temperature of RTA treatment in the temperature range between 1250?C and 1400?C. The concentration at maximal temperature is equal to 4.5 × 1013 cm?3. The experimental results were compared with concentrations of VOn complexes in silicon wafers obtained using ab-initio calculations combined with rate equation modelling. The simulated concentration of VO4 corresponds well to the measured concentration. The bulk microdefect density increases with increasing VO4 concentration. The vacancies stored in VOn complexes after RTA are slowly released during further annealing and enhance oxide precipitation.
关键词： VO4 complexes,silicon wafers,Rapid thermal annealing,FTIR spectroscopy,oxygen precipitation
更新于2025-09-09 09:28:46