Optical properties of InGaN/GaN nanocolumns in yellow‐to‐red region

Abstract

The optical properties of InGaN/GaN multiple‐quantum‐well (MQW) nanocolumns whose emission wavelength is in the yellow‐to‐red region (2.1 ∼ 2.3 eV) have been investigated using time‐resolved photoluminescence (PL) measurements. The analysis of the PL decay curves using a stretched exponential function shows that the radiative and nonradiative rates in the red region are almost the same as those in the yellow region. Long‐lived migrating carriers also contribute the strong PL intensity in the red region. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Alternating-Current InGaN/GaN Tunnel Junction Nanowire White-Light Emitting Diodes

“…With the use of tunnel junction, the resistive p -GaN contact layer can be replaced by an n -GaN contact, leading to significantly reduced device resistance, ,− voltage loss, and heating effect. , Tunnel junction also enables the stacking of multiple p – n junctions/LEDs, ,,− providing the unique opportunity of repeated carrier usage. ,, As such, high power operation can be achieved at low injection current, leading to enhanced efficiency and reduced efficiency droop. , Various design schemes, including GaN/Al­(Ga)­N/GaN, − , GaN/InGaN/GaN, ,,− and GaN/GdN/GaN , tunnel junctions have been implemented in GaN-based LED structures. However, the tunneling probability has been severely limited by the difficulty in creating a highly doped p -region. ,, Recently, it has been demonstrated that dopant incorporation can be significantly enhanced in nanowire structures, due to the much reduced formation energy in the near-surface region. − Moreover, compared to conventional GaN quantum well devices, GaN nanowire LEDs can exhibit significantly reduced dislocation densities and polarization fields. − Nanowire LEDs with tunable, multicolor emission have been demonstrated, which can be epitaxially grown on extremely low cost, large area Si substrates. ,− In spite of these intensive studies, the incorporation of tunnel junction in nanowire LEDs has not been reported to our knowledge.…”