Electrical Measurement of Recombination Lifetime in Blue Light Emitting Diodes

Awaah, M. A.; Nana, Roger; Das, K.

doi:10.1557/proc-829-b2.11

Cited by 2 publications

(2 citation statements)

References 11 publications

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“…As noted previously, these high values of the ideality factor indicate that the diodes studied were highly non-ideal [3,5,7,8]. Reverse leakage currents of 11 A/cm 2 for the blue and 12 A/cm 2 for the yellow LED were observed at a reverse bias of 5 V. Semilogarithmic plots of I-V characteristics yielded values of the ideality factors ranging from 3.97 to 5.92 for these LEDs.…”

Section: Resultssupporting

confidence: 62%

Electrical Characterization of GaN Based Ultraviolet and Blue Light Emitting Diodes

et al. 2006

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Gallium nitride based ultraviolet (UV) and blue AlGaN/GaN/AlGaN double heterojunction structure light emitting diodes (LEDs) were electrically characterized using current-voltage (I-V) and capacitance-voltage (C-V) measurements as a function of frequency. An analysis of logarithmic plots of the forward I-V characteristics indicated that current in these diodes was proportional to x V , as opposed to nkT qV e / , where x was observed to be either 1 or 2 at low biases increasing to as high as 40 at higher biases. The dependence of diode forward current on x V is likely to be due to space charge limited current in the presence of a high concentration of deep level states in the bandgap. The concentration of deep states and their position in the band gap were extracted from these logarithmic plots. For both the blue and the UV LEDs, several closely spaced levels were obtained, located most likely in the range between E V and E V + 0.5 eV with concentrations of the order of 10 16 /cm 3 to 10 17 /cm 3 . Capacitance-voltage measurements as a function of frequency (200 Hz -1 MHz) at room temperature yielded a density of approximately 1 x 10 15 cm -3 located at 0.46 eV above the valence band-edge for both the UV and blue LED. Even though the location of these deep states from the I-V and C-V measurements are within the same range, the two orders magnitude difference in the concentration of deep states is not well understood at this point. Mater. Res. Soc. Symp. Proc. Vol. 955

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Section: Resultssupporting

confidence: 62%

Electrical Characterization of GaN Based Ultraviolet and Blue Light Emitting Diodes

et al. 2006

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“…It was inferred from these observations that conduction in these diodes was due to space‐charge‐limited (SCL) transport in the presence of traps 14, 15. Determination of approximate concentrations of trap states and their location in the bandgap were also obtained from an analysis of the SCL I – V characteristics 16. It should be noted that traps are essentially deep states located closer to the conduction or the valence‐band edge as opposed to midgap states that act as efficient recombination centers 17.…”

Section: Introductionmentioning

confidence: 99%

Effect of deep‐level states on current–voltage characteristics and electroluminescence of blue and UV light‐emitting diodes

Nana

Gnanachchelvi

Awaah

et al. 2010

Physica Status Solidi (a)

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Phone: 334 727 8994, Fax: 334 724 4806.Current-voltage (I-V) characteristics and electroluminescence spectra of several ultraviolet and blue light-emitting diodes (LEDs) emitting nominally at 380, 400, 430, and 468 nm were studied. These diodes exhibited an Ohmic regime at low forward biases; then the current increased sharply as bias increased. Several changes in the slope of logarithmic I-V plots indicated that, I / V x . These changes in the slope were interpreted as single-carrier space-charge-limited (SCL) transport across the diode active region. As bias increased the deep states were filled and for the 400-and 468-nm diodes ideality factors of $2 were obtained. This indicated that, as bias increased the transport mechanism changed from SCL conduction to recombination of injected carriers in the spacecharge region. For the 380-and 430-nm diodes, ideality factors >>2 were obtained, although the observed electroluminescence spectrum indicated substantial radiative recombination. For the diode emitting at 430 nm, several peaks including the major peak at $424 nm appeared to have resulted from transitions between the conduction-band edge and deep states, identified from the I-V characteristics, likely to be associated with Zn doping of the InGaN active region. Deep states in the other diodes appeared to be ineffective in the radiative recombination process.

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Electrical Measurement of Recombination Lifetime in Blue Light Emitting Diodes

Cited by 2 publications

References 11 publications

Electrical Characterization of GaN Based Ultraviolet and Blue Light Emitting Diodes

Electrical Characterization of GaN Based Ultraviolet and Blue Light Emitting Diodes

Effect of deep‐level states on current–voltage characteristics and electroluminescence of blue and UV light‐emitting diodes

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