Scalable Nanowire Photonic Crystals: Molding the Light Emission of InGaN.

To date, there have been no efficient semiconductor light emitters operating in the green and amber wavelengths. This study reports on the synthesis of InGaN nanowire photonic crystals, including dot-in-nanowires, nanotriangles, and nanorectangles with precisely controlled size, spacing, and morphology, and further demonstrates that bottom-up InGaN photonic crystals can exhibit highly efficient and stable emission. The formation of stable and scalable band edge modes in defect-free InGaN nanowire photonic crystals is directly measured by cathodoluminescence studies. The luminescence emission, in terms of both the peak position (λ ≈ 505 nm) and spectral linewidths (full-width-half-maximum ≈ 12 nm), remains virtually invariant in the temperature range of 5-300 K and under excitation densities of 29 W cm−2 to 17.5 kW cm−2. To the best of our knowledge, this is the first demonstration of the absence of Varshni and quantum-confined Stark effects in wurtzite InGaN light emitters-factors that contribute significantly to the efficiency droop and device instability under high-power operation. Such distinct emission properties of InGaN photonic crystals stem directly from the strong Purcell effect, due to efficient coupling of the spontaneous emission to the highly stable and scalable band-edge modes of InGaN photonic crystals, and are ideally suited for uncooled, high-efficiency light-emitting-diode operation. [ABSTRACT FROM AUTHOR]