Voltage Modulated Electroluminescence and Forward Bias Impedance Characteristics of Light Emitting Semiconductor Devices
Voltage modulated electroluminescence and forward bias impedance characteristics of AlGaInP based multi quantum well light emitting devices are studied in frequency (up to 1 MHz) and temperature domain. We observed inductive like reactance for low frequencies and high biases. A frequency dependent modulated light output has also been observed which also increases when modulation frequency is lowered. We explained the occurrence of inductive response and correlated modulated light output at low frequencies by considering defect participation in fast radiative recombination process. Temperature variation of reactance and modulated light output supports our understanding based on defect contribution model. However, with temperature change, dynamics of charge carriers inside the quantum well starts to affect the optical as well as electrical response. This work can be useful in improving the efficiency of light emitting devices for their applications involving direct modulation. This can also help in understanding the physics of a semiconductor junction under high carrier injection.
KeywordsLight emitting devices Impedance spectroscopy and sub-bandgap defects
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Authors wish to thank IISER-Pune for startup funding of the laboratory infrastructure and Department of Science and Technology, India for DST Nano Unit Grant SR/NM/NS-42/2009. KB is thankful to CSIR, India for research fellowship.