Nano-indentation study of dislocation evolution in GaN-based laser diodes.

The slip systems and motion behavior of dislocations induced by nano-indentation technique in GaN-based LDs were investigated. Dislocations with burgers vector of b = 1/3 <11 3> were introduced on either {11 2} <11 3>, or {1 01} <11 3> pyramidal slip systems in the upper p-GaN layer. Besides, {0001} <11 0> basal slip system was also activated.

Modulation of Remote Epitaxial Heterointerface by Graphene-Assisted Attenuative Charge Transfer.

Remote epitaxy (RE), substrate polarity can "penetrate" two-dimensional materials (2DMs) and act on the epi-layer, showing a prospective universal growth strategy. However, essentially, the role that 2DMs plays in RE has not been deeply investigated so far. Here, the RE of single-crystal films on the weakest polarity/iconicity substrate is realized to reveal its essence physical properties.

Effect of Graded-Indium-Content Superlattice on the Optical and Structural Properties of Yellow-Emitting InGaN/GaN Quantum Wells.

We have improved the material quality of the high indium composition InGaN/GaN multiple quantum wells (MQWs) grown on free-standing GaN substrates using the graded-indium-content superlattice. We found that by adopting a graded-indium-content superlattice structure, the spectral FWHM of the yellow emitting InGaN/GaN MQW was reduced from 181 meV to 160 meV, and the non-radiative recombination lifetime increased from 13 ns to 44 ns. Besides, the graded-indium-content superlattice can mitigate strain relaxation in high indium composition MQWs as shown by the TEM diffraction patterns.

Nucleation and growth of (10͞11) semi-polar AlN on (0001) AlN by Hydride Vapor Phase Epitaxy.

Wurtzite AlN is widely used for deep ultraviolet optoelectronic devices (DUV), which are generally grown along the [0001]-direction of the wurtzite structure on currently available substrates. However, huge internal electrostatic fields are presented within the material along [0001] axis induced by piezoelectric and spontaneous polarization, which has limited the internal quantum efficiency of AlN based DUV LEDs dramatically. The internal fields can be strongly reduced by changing the epitaxial growth direction from the conventional polar c-direction into less polar crystal directions.