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Ion-Implant Isolated Vertical GaN p-n Diodes Fabricated with Epitaxial Lift-Off From GaN Substrates
摘要： Ion-implant isolated vertical GaN p-n junction diodes fabricated with epitaxial lift-off (ELO) from GaN substrates are demonstrated. For the ELO process, a band-gap selective photoelectrochemical (PEC) wet etch with a pseudomorphic InGaN release layer is utilized. Compared with devices isolated using mesa etching, the ion-implant isolated devices exhibit more ideal forward current–voltage characteristics and lower leakage currents. Devices are also compared with and without ELO processing. Devices measured after ELO processing and mounting to metallized carrier substrates show similar electrical performance to GaN-on-GaN control samples without ELO processing. No indication of material quality degradation is found on the ELO devices. The ELO devices exhibit turn-on voltages of 3.15 V (at a current density of 100 A cm?2), with specific on resistance (Ron) of 0.52 mΩ cm2 at 4.8 V and breakdown voltage (Vbr) approximately of 750 V.
关键词： ion-implant isolation,epitaxial lift-off,GaN p-n junctions,p-GaN ohmic contact
更新于2025-09-23 15:22:29
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Effects of post bonding annealing on GaAs//Si bonding interfaces and its application for sacrificial-layer-etching based multijunction solar cells
摘要： By using the sacrificial layer (SL) etching, GaAs substrates are separated from III–V epi substrate//Si substrate junctions that are made by surface activated bonding (SAB) technologies. The post-bonding low-temperature (300-?C) annealing plays an essential role in achieving a promising (～90%) bonding yield. The effects of the post-bonding annealing are investigated by hard X-ray photoemission spectroscopy and current–voltage measurements of GaAs//Si bonding interfaces. It is found that the concentration of oxygen atoms at interfaces is reduced and the resistance decreases to 1.6–2.1 m??cm2 by the low-temperature annealing. Aluminum fluoride complexes are not observed by X-ray photoelectron spectroscopy on the exposed surfaces of separated GaAs substrates. The roughness average of the surfaces is ≈0.25–0.30 nm. The characteristics of double junction cells fabricated on the GaAs//Si junctions prepared by the SL etching are almost the same as those of cells fabricated by dissolving GaAs substrates after bonding. These results indicate that multijunction cells could be fabricated in a process sequence compatible with reuse of GaAs substrates by combining the SL etching and SAB.
关键词： Sacrificial layer etching,GaAs//Si double junction cells,Surface activated bonding,Low temperature annealing,Epitaxial lift-off
更新于2025-09-23 15:19:57
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Multiple epitaxial lift-off of stacked GaAs solar cells for low-cost photovoltaic applications
摘要： This paper presents a multilayer peeling from a stacked cell structure as an approach for the cost reduction of III–V solar cells. We demonstrate the separation of two-layer stacked GaAs solar cells with Al(Ga)As release layers on the GaAs substrate into individual layers without cracks. The cells in each layer peeled from the stacked structure show equivalent device performances. Thermal cycling tests with repeated heating to 85 °C and cooling to ?40 °C show that the flexible GaAs thin-film cell exhibits a high durability against temperature changes. Further, a damp heat test conducted at 85 °C and 85% humidity indicates that the cell has long-term stability. These results suggest that the flexible GaAs thin-film cells fabricated by peeling from stacked structures have a high reliability and prove that the separation of the stacked cell structures into individual layers is effective in fabricating low-cost III–V solar cells.
关键词： epitaxial lift-off,cost reduction,damp heat test,photovoltaic applications,thermal cycling,GaAs solar cells
更新于2025-09-23 15:19:57
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Monolithic integration of visible GaAs and near-infrared InGaAs for multicolor photodetectors by using high-throughput epitaxial lift-off toward high-resolution imaging systems
摘要： In this study, multicolor photodetectors (PDs) fabricated by using bulk p-i-n-based visible GaAs and near-infrared inGaAs structures were monolithically integrated through a high-throughput epitaxial lift-off (ELO) process. To perform multicolor detection in integrated structures, GaAs PDs were transferred onto inGaAs pDs by using a Y2o3 bonding layer to simultaneously detect visible and near-infrared photons and minimize the optical loss. As a result, it was found that the GaAs top PD and InGaAs bottom PD were vertically aligned without tilting in x-ray diffraction (XRD) measurement. A negligible change in the dark currents for each PD was observed in comparison with reference PDs through electrical characterization. Furthermore, through optical measurements and simulation, photoresponses were clearly revealed in the visible and near-infrared band for the material’s absorption region, respectively. Finally, we demonstrated the simultaneous multicolor detection of the visible and near-infrared region,which implies individual access to each PD without mutual interference. These results are a significant improvement for the fabrication of multicolor PDs that enables the formation of bulk-based multicolor PDs on a single substrate with a high pixel density and nearly perfect vertical alignment for high-resolution multicolor imaging.
关键词： high-resolution imaging,multicolor photodetectors,InGaAs,epitaxial lift-off,GaAs
更新于2025-09-12 10:27:22