Three series of GaInN/GaN light-emitting diodes (LEDs) emitting at 400nm with

well widths varying between 3 and 18nm were grown on sapphire, ultra-low

dislocation density GaN templates, and free-standing GaN substrates.

Photoluminescence and pulsed electroluminescence were systematically

investigated. Photoluminescence spectroscopy showed a noteworthy increase in

radiative efficiency for GaInN/GaN double-heterostructures or wide wells on low

dislocation density substrates. The electroluminescence properties significantly

differ for wide well LEDs on sapphire and on low defect density substrates but

were comparable for LEDs containing thin single quantum wells. Increasing well

width leads to decreasing quantum efficiency at all currents for LEDs on sapphire.

The highest overall efficiency was obtained for LEDs with 11nm and 18nm thick

DHs on GaN templates and free-standing GaN substrates, respectively, at current

densities above 200 A/cm2.

Influence of Substrate Dislocation Density and Quantum Well Width on the

Quantum Efficiency of Violet-Emitting Gainn/GaN Light-Emitting Diodes.

T.Passow, M.Maier, M.Kunzer, C.C.Leancu, S.Liu, J.Wiegert, R.Schmidt,

K.Köhler, J.Wagner: Physica Status Solidi C, 2009, 6[S2], S833-6