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High Internal Quantum Efficiency Ultraviolet Emission from Phase-Transition Cubic GaN Integrated on Nanopatterned Si(100)
journal contribution
posted on 2018-01-08, 00:00 authored by Richard Liu, Richard Schaller, Chang Qiang Chen, Can BayramUltraviolet emission characteristics
of cubic (c-) GaN enabled through hexagonal-to-cubic phase transition
are reported. Substrate patterning and material growth are shown to
affect phase purity and emission characteristics of c-GaN as studied
by electron backscatter diffraction, and photo- and cathodoluminescence,
respectively. Raman study shows a tensile strain in the c-GaN. Time-resolved
photoluminescence reveals c-GaN band edge emission decay time of 11
ps. The ultraviolet emissions from both phases of GaN are linearly
polarized in the same direction, which is along the ⟨112̅0⟩
and ⟨110⟩ directions of hexagonal GaN and c-GaN, respectively.
Temperature-dependent (5.7 to 280 K) cathodoluminescence studies reveal
an internal quantum efficiency of ∼29% at room temperature
along with intrinsic and extrinsic defect energy levels of ∼124
and ∼344 meV, respectively, of the phase-transition c-GaN.
Using the IQE value and carrier decay lifetime, a radiative lifetime
of 38 ps is extracted. Overall, photonic properties of phase-transition
c-GaN and their dependence on substrate patterning and material growth
are reported.