24 research outputs found
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Increased Optoelectronic Quality and Uniformity of Hydrogenated p-InP Thin Films
The thin-film vapor-liquid-solid (TF-VLS) growth technique presents a promising route for high quality, scalable, and cost-effective InP thin films for optoelectronic devices. Toward this goal, careful optimization of material properties and device performance is of utmost interest. Here, we show that exposure of polycrystalline Zn-doped TF-VLS InP to a hydrogen plasma (in the following referred to as hydrogenation) results in improved optoelectronic quality as well as lateral optoelectronic uniformity. A combination of low temperature photoluminescence and transient photocurrent spectroscopy was used to analyze the energy position and relative density of defect states before and after hydrogenation. Notably, hydrogenation reduces the relative intragap defect density by 1 order of magnitude. As a metric to monitor lateral optoelectronic uniformity of polycrystalline TF-VLS InP, photoluminescence and electron beam induced current mapping reveal homogenization of the grain versus grain boundary upon hydrogenation. At the device level, we measured more than 260 TF-VLS InP solar cells before and after hydrogenation to verify the improved optoelectronic properties. Hydrogenation increased the average open-circuit voltage (VOC) of individual TF-VLS InP solar cells by up to 130 mV and reduced the variance in VOC for the analyzed devices
Updated sustainability status of crystalline siliconâbased photovoltaic systems: Lifeâcycle energy and environmental impact reduction trends
Comparative effect of distal and proximal intestinal resection and bypass on the rat exocrine pancreas
Stretchable micro-scale concentrator photovoltaic module with 15.4% efficiency for three-dimensional curved surfaces
Estimation of losses in solar energy production from air pollution in China since 1960 using surface radiation data
Exploring the competition between variable renewable electricity and a carbon-neutral baseload technology
Electrical and optical characterizations of InAs/GaAs quantum dot solar cells
© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. The electrical and optical characterizations of InAs/GaAs quantum dot solar cells (QDSCs) were investigated by frequency dependent capacitanceâvoltage (CâV) measurements and photoreflectance (PR) spectroscopy. The CâV results confirmed that the frequency dependent junction capacitance (C j ) of QDSC is sensitive to the carrier exhaustion process through trapping and recapturing in the strain-induced defects and QD states caused by the interface strain between InAs and GaAs materials. As a result, at a low frequency (†200 kHz), the C j of the QDSCs decreased with increasing InAs deposition thickness (Ξ), leading to the decrease in carrier concentration (N d ) of the n-GaAs absorber layer due to the carrier losses processes caused by the trapping and re-capturing in the defects and the relatively large QDs. At Ξ †2.0 ML, the p-n junction electric field strength (F pn ) of the QDSCs which was evaluated by PR spectra decreased with increasing excitation photon intensity (I ex ) due to the typical field screening effect in the SC structure. On the other hand, the F pn of QDSCs with Ξ â„ 2.5 ML approached a constant value with a relatively high I ex , which suggests that the decrease in photo-generated carriers in the QDSC was caused by the re-capturing and trapping process