AlGaAs/GaAs photovoltaic converters for high power narrowband radiation

AlGaAs/GaAs-based laser power PV converters intended for operation with high-power (up to 100 W/cm(2)) radiation were fabricated by LPE and MOCVD techniques. Monochromatic (lambda = 809 nm) conversion efficiency up to 60% was measured at cells with back surface field and low (x = 0.2) Al concentration 'window'. Modules with a voltage of 4 V and the efficiency of 56% were designed and fabricated

High Intensity Low Temperature (HILT) performance of space concentrator GaInP/GaInAs/Ge MJ SCs

In the work, the results of an investigation of GaInP/GaInAs/Ge MJ SCs intended for converting concentrated solar radiation, when operating at low temperatures (down to -190 degrees C) are presented. A kink of the cell I-V characteristic has been observed in the region close to V-oc starting from -20 degrees C at operation under concentrated sunlight. The causes for its occurrence have been analyzed and the reasons for formation of a built-in potential barrier for majority charge carriers at the n-GaInP/n-Ge isotype hetero-interface are discussed. The effect of charge carrier transport in n-GaInP/n-p Ge heterostructures on MJ SC output characteristics at low temperatures has been studied including EL technique

Increasing the quantum efficiency of InAs/GaAs QD arrays for solar cells grown by MOVPE without using strain-balance technology

Research into the formation of InAs quantum dots (QDs) in GaAs using the metalorganic vapor phase epitaxy technique ispresented. This technique is deemed to be cheaper than the more often used and studied molecular beam epitaxy. The bestconditions for obtaining a high photoluminescence response, indicating a good material quality, have been found among awide range of possibilities. Solar cells with an excellent quantum ef?ciency have been obtained, with a sub-bandgapphoto-response of 0.07 mA/cm2per QD layer, the highest achieved so far with the InAs/GaAs system, proving the potentialof this technology to be able to increase the ef?ciency of lattice-matched multi-junction solar cells and contributing to abetter understanding of QD technology toward the achievement of practical intermediate-band solar cells

Experimentelle Untersuchung zur Wirkung von Druckdifferenzen in Melkzeugen mit periodischem und kontinuierlichem Lufteinlass auf Merkmale der Melkbarkeit und Zitzenbeschaffenheit

Beim maschinellen Milchentzug bei 18 Kuehen wurden die Faktoren periodischer- bzw. kontinuierlicher Lufteinsatz mit 4 verschiedenen Druckverhaeltnissen im Pulsraum waehrend der Druckphase (=Druckdifferenz) vergleichend geprueft. Die Gesamtmilchmengenleistungen und die Maschinenhauptgemelke blieben von den untersuchten Kombinationen unbeeinflusst. Mit zunehmender Druckdifferenz wurde eine Zunahme der Nachgemelke festgestellt. Kutimetermessungen an der Zitze zeigten keine chronischen Reaktionen auf die Behandlungen. Mit zunehmender Druckdifferenz wurden die Messwerte aber gleich nach dem Melken kleinerAvailable from: Hohenheim Univ., Stuttgart (Germany, F.R.). Universitaetsbibliothek / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman