Photocarrier dynamics near V-shaped pits in InxGa1−xN/GaN multiple quantum wells

- Correlations between carrier dynamics and structural defects of InGaN MQWs exist.
- PL intensity is much weaker in the V-shaped pits than in the regular c-plane.
- Blue-shifted photoluminescence spectrum is not observed at the V-pits.
- A kinetic model including carriers recombination and diffusion is presented.
- The model estimates the nonradiative recombination time as 10 ps at the V-pits.

Space- and time-resolved photoluminescence (PL) has been employed to investigate correlations between the carrier dynamics and structural defects known as V-shaped pits in InGaN/GaN multiple quantum wells (MQWs). The pits exhibit much lower PL intensity compared to MQWs of the normal c-plane indicating a high density of nonradiative recombination centers in the pits. However, the PL peak wavelength, which is expected to experience a blueshift at the pits due to the stronger confinement effect and reduced quantum-confined Stark effect, do not show any spatial dependence that is correlated with the defects. This is ascribed to dominant ultrafast (<10 ps) nonradiative recombination at the pits and additional diffusion into the c-plane leading to radiative recombination. By contrast, weak but clear correlations between the pits and PL decay time were observed on nanosecond timescales. This can be explained by a kinetic model that includes the nonradiative recombination and diffusion of carriers at the pits.