Dominance of tunneling current and band filling in InGaN/AlGaN double heterostructure blue light-emitting diodes

Abstract

Measurement of the room temperature forward bias current-voltage behavior of InGaN/AlGaN double heterostructure blue light-emitting diodes demonstrates a significant departure from the usual Is exp(qV/ nkT) behavior where n is the ideality factor which varies between 1 and 2. The observed current-voltage behavior at room temperature may be represented as I=2.7×10−11 exp(5.7V) which suggests a tunneling mechanism. Measurement of the electroluminescence for currents from 0.5 to 100 mA demonstrates that the emission peak shifts to higher energy while increasing in intensity. The shifting peak spectra is due to band filling, a process which results from the injection of holes via tunneling into an empty acceptor impurity band and vacant valence band tails. At currents near 100 mA, a non-shifting band-to-band emission approaches the intensity of the shifting peak spectra. The active layer of these diodes is codoped with both the donor Si and the acceptor Zn.

Polarization-induced confinement of continuous hole-states in highly pumped, industrial-grade, green InGaN quantum wells

“…[4][5][6][7][8] At the same time, a significant broadening and an apparent asymmetry of the emission band are observed, which indicates band-filling. 20,21 Second, an additional, broad peak is observed at much higher energies, which we call the Confined Hole Continuum (CHC) luminescence. This particular luminescence is not associated with any distinct excitation channel as the photoluminescence excitation (PLE) spectrum from Fig.…”

Effect of long-term aging on series resistance and junction conductivity of high-power InGaN light-emitting diodes

“…(The absolute errors for the values of the series resistance and energy parameter are determined by the method of least-squares used for the fitting of the experimental data to linear dependences.) The estimated values of the characteristic energy imply the values of the ideality factor are well above 2, which indicate the domination of injection due to tunnelling [17,18]. Differently from the series resistance, the above approach is seen to reveal no change in the energy parameter within the accuracy of the experiment.…”

“…The observed variation of the I-V characteristics was analysed within a generalized Shockley equation with exponential contributions of diffusion, recombination, and tunnel injection mechanisms peculiar to InGaN LEDs [17][18][19]:…”

In situ growth of p and n-type graphene thin films and diodes by pulsed laser deposition

“…Ideality factors greater than 10 have been reported for oxide based p-n diodes 28 and such high values have been attributed to deep-level-assisted tunneling. 29 In fact, the tunneling process may be the dominating conduction mechanism in our p-n junction due to presence of high density of carriers in the individual p-and n-type graphene films as evident from the high reverse current, which is even higher at 443 K due to the decreased depletion layer width. In spite of the weak diode performance, the obtained results suggest that p-n diodes can be fabricated using PLD deposited n-and p-type graphene films and one can expect better performance once the thickness and conductivity of the films are optimized.…”