Correlation between dark current RTS noise and defects for AIGalnP multiple-quantum-well laser diode

The correlation model between dark current RTS noise and defects for A1GalnP multiple-quantum-well laser diode is derived. Experimental results show that dark current RTS noise caused carrier number fluctuations at the interface of the heterojunction in the active region. According to this correlation model, the defect types are determined, and the defects＇ energy levels are quantitatively determined. The comer frequency of RTS noise power spectral density is analyzed. The experimental results are in good agreement with the theoretical. This result provided an effective method for estimating the deep-level traps in the active region of A1GaInP multiple quantum well laser diode.     

Fill factor as a probe of current‐matching for GaInP2/GaAs tandem cells in a concentrator system during outdoor operation

Designing a tandem solar cell for use in a concentrator system is challenging because: (a) the conditions are variable, so solar cells rarely operate under optimal conditions, and (b) the conditions are not controlled, so any design problems are difficult to characterize. Here, we show how the fill factor can be used as a diagnostic tool to either verify correct system design and operation or to help identify a problem. We give particular attention to the detection of spectral skewing by the concentrator optics, as this can reduce the performance of GaInP₂/GaAs tandem cells and is difficult to characterize. The conclusions are equally valid for GaInP₂/GaAs/Ge triple‐junction cells. Copyright © 2007 John Wiley & Sons, Ltd.