Search results for "Internal quantum efficiency"
showing 5 items of 5 documents
High-efficiency silicon-compatible photodetectors based on Ge quantum dots
2011
We report on high responsivity, broadband metal/insulator/semiconductor photodetectors with amorphous Ge quantum dots (a-Ge QDs) as the active absorbers embedded in a silicon dioxide matrix. Spectral responsivities between 1-4 A/W are achieved in the 500-900 nm wavelength range with internal quantum efficiencies (IQEs) as high as ∼700%. We investigate the role of a-Ge QDs in the photocurrent generation and explain the high IQE as a result of transport mechanisms via photoexcited QDs. These results suggest that a-Ge QDs are promising for high-performance integrated optoelectronic devices that are fully compatible with silicon technology in terms of fabrication and thermal budget. © 2011 Amer…
Temperature Dependent Quantum Efficiencies in Multicrystalline Silicon Solar Cells
2015
Abstract Several field studies comparing modules based on Elkem Solar Silicon ® (ESS ® ) cells with reference modules based on non-compensated virgin polysilicon show that the compensated ESS ® modules outperform the reference modules with comparable installed capacity under certain operating conditions. At high temperatures and high irradiation conditions the modules based on compensated silicon produce more energy than the reference modules. In order to increase the understanding of the observed effect cells are studied at different temperatures by the means of IV-characteristics as well as quantum efficiencies. Quantum efficiency measurements show that the main difference between ESS ® c…
Transient photoresponse and incident power dependence of high-efficiency germanium quantum dot photodetectors
2012
We report a systematic study of time-resolved and power-dependent photoresponse in high-efficiency germanium quantum dot photodetectors (Ge-QD PDs), with internal quantum efficiencies greater than 100 over a broad wavelength, reverse bias, and incident power range. Turn-on and turn-off response times (τ on and τ off) are shown to depend on series resistance, bias, optical power, and thickness (W QD) of the Ge-QD layer, with measured τ off values down to ∼40 ns. Two different photoconduction regimes are observed at low and high reverse bias, with a transition around -3 V. A transient current overshoot phenomenon is also observed, which depends on bias and illumination power. © 2012 American …
Role of Ge nanoclusters in the performance of photodetectors compatible with Si technology
2013
In this work, we investigate the spectral response of metal-oxide- semiconductor photodetectors based on Ge nanoclusters (NCs) embedded in a silicon dioxide (SiO2) matrix. The role of Ge NC size and density on the spectral response was evaluated by comparing the performance of PDs based on either densely packed arrays of 2 nm-diameter NCs or a more sparse array of 8 nm-diameter Ge NCs. Our Ge NC photodetectors exhibit a high spectral responsivity in the 500-1000 nm range with internal quantum efficiency of ~ 700% at - 10 V, and with NC array parameters such as NC density and size playing a crucial role in the photoconductive gain and response time. We find that the configuration with a more…
Room-temperature efficient light detection by amorphous Ge quantum wells
2013
In this work, ultrathin amorphous Ge films (2 to 30 nm in thickness) embedded in SiO2 layers were grown by magnetron sputtering and employed as proficient light sensitizer in photodetector devices. A noteworthy modification of the visible photon absorption is evidenced due to quantum confinement effects which cause both a blueshift (from 0.8 to 1.8 eV) in the bandgap and an enhancement (up to three times) in the optical oscillator strength of confined carriers. The reported quantum confinement effects have been exploited to enhance light detection by Ge quantum wells, as demonstrated by photodetectors with an internal quantum efficiency of 70%. © 2013 Cosentino et al.