Lateral charge carrier diffusion in InGaN quantum wells

Abstract

We investigated lateral charge carrier transport in indium gallium nitride InGaN/GaN multi-quantum wells for two different samples, one sample emitting green light at about 510 nm and the other emitting cyan light at about 470 nm. For the cyan light emitting sample we found a diffusion constant of 1.2 cm2/s and for the green light emitting sample 0.25 cm2/s. The large difference in diffusion constant is due to a higher point defect density in the green light emitting quantum wells (QWs) as high indium incorporation tends to reduce material quality

Efficiency of True-Green Light Emitting Diodes: Non-Uniformity and Temperature Effects

“…In order to assess whether the small recombination volume may be attributed to extended defects, we assume the sw-emission to originate from the carriers collected from the area of about around each of the defects, where L d is the carrier diffusion length, D a is the ambipolar diffusion coefficient, and τ d is the differential carrier life time. Using experimental values D a ~ 0.25 cm 2 /s [ 31 ] and τ d ~ 20 ns [ 23 ], typical for green InGaN LEDs operating at low currents, we obtain ~ 5 × 10 −9 cm 2 . In this case, the density of the extended defects necessary to provide the ratio is ~10 6 cm −2 , which may be tentatively associated with the density of V-pits.…”

Wavelength‐dependent determination of the recombination rate coefficients in single‐quantum‐well GaInN/GaN light emitting diodes

“…According to our current understanding, the lower carrier diffusivity in In‐rich GaInN layers 38 should make it less likely for the carriers to move laterally in the quantum wells and reach non‐radiative recombination centers 39. Therefore, we would expect to see a decreasing trend of the RRC A with increasing wavelength/decreasing bandgap energy.…”

Influence of V-pits on the efficiency droop in InGaN/GaN quantum wells

“…The excited carriers tend to diffuse laterally on InGaN/GaN in-plane QWs until they recombine [24,25]. As clearly seen from the transmission electron microscope image in Fig.…”

“…This not only supports the role of V-pits as non-recombination centers, but also suggests the carrier screening by V-pits preventing the carriers from recombining with TDs. In other words, the excited carriers on in-plane QWs tend to diffuse laterally until they recombine radiatively or non-radiatively [24,25]. It is likely that the carriers in the vicinity of TDs are destined to nonradiately recombine with TDs unless TD coexists with V-pit.…”