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Creators/Authors contains: "Speck, James_S"

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  1. ; ; ; ; ; ; (, Applied Physics Letters)
    Time-resolved and quasi-cw photoluminescence (PL) spectroscopy was applied to measure the internal quantum efficiency (IQE) of c-plane InGaN single quantum wells (QWs) grown on sapphire substrates using metal-organic chemical vapor deposition. The identical temperature dependence of the PL decay times and radiative recombination times at low temperatures confirmed that the low temperature IQE is 100%, which allowed evaluation of the absolute IQE at elevated temperatures. At 300 K, the IQE for QWs emitting in green and green–yellow spectral regions was more than 60%. The weak nonradiative recombination in QWs with a substantial concentration of threading dislocations and V-defects (∼2 × 108 cm−2) shows that these extended defects do not notably affect the carrier recombination. 
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  2. ; ; ; ; ; ; ; (, Optics Express)
    We reported significant improvements in device speed by reducing the quantum barrier (QB) thicknesses in the InGaN/GaN multiple quantum well (MQW) photodetectors (PDs). A 3-dB bandwidth of 700 MHz was achieved with a reverse bias of -6 V. Carrier escape lifetimes due to carrier trapping in the quantum wells (QWs) were obtained from both simulation and experimental fitting, identifying carrier trapping as the major speed limiting factor in the InGaN/GaN MQW PDs. 
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