Effect of Deep Centers on Charge-Carrier Confinement in InGaN/GaN Quantum Wells and on LED Efficiency

Journal Article · Sun Jul 15 04:00:00 EDT 2018 · Semiconductors

DOI:https://doi.org/10.1134/S1063782618070035· OSTI ID:22749878

Bochkareva, N. I.

The deep-center-assisted tunneling of carriers in p–n structures of light-emitting diodes (LEDs) with InGaN/GaN quantum wells (QWs) makes smaller the effective height of the injection barrier, but leads to a dependence of the radiation efficiency on the density and energy spectrum of defects in GaN. In the case of hopping conduction across the space charge region, the forward voltage mainly drops near the QW boundary, where the density of deep states at the quasi Fermi-level is the lowest. As a result, band bending at the boundary decreases, and, with increasing current, the direction of the electric field also changes, which leads to a weaker confinement of holes, to their non-radiative recombination in the n barrier, and to an efficiency droop. The low efficiency of green GaN LEDs is associated with the dominance of deep centers and insufficient density of shallow centers in the energy spectrum of defects in barrier layers near the boundaries with the QW. The proposed model is confirmed by the stepwise experimental dependences of the current, capacitance and efficiency of green and blue LEDs in the case of forward bias, which reflect the contribution of color centers responsible for the defect photoluminescence bands in GaN.

• OSTI ID: 22749878
• Journal Information: Semiconductors, Journal Name: Semiconductors Journal Issue: 7 Vol. 52; ISSN SMICES; ISSN 1063-7826
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHARGE CARRIERS
COLOR CENTERS
CONFINEMENT
DEFECTS
EFFICIENCY
ELECTRIC FIELDS
ENERGY SPECTRA
FERMI LEVEL
GALLIUM NITRIDES
LIGHT EMITTING DIODES
QUANTUM WELLS
SPACE CHARGE
TUNNEL EFFECT