Abstract
Optimization of internal quantum efficiency (IQE) for InGaN quantum wells (QWs) light-emitting diodes (LEDs) is investigated. Staggered InGaN QWs with large electron-hole wavefunction overlap and improved radiative recombination rate are investigated for nitride LEDs application. The effect of interface abruptness in staggered InGaN QWs on radiative recombination rate is studied. Studies show that the less interface abruptness between the InGaN sub-layers will not affect the performance of the staggered InGaN QWs detrimentally. The growths of linearly-shaped staggered InGaN QWs by employing graded growth temperature grading are presented. The effect of current injection efficiency on IQE of InGaN QWs LEDs and other approaches to reduce dislocation in InGaN QWs LEDs are also discussed. The optimization of both radiative efficiency and current injection efficiency in InGaN QWs LEDs are required for achieving high IQE devices emitting in the green spectral regime and longer.
Highlights
Received 19 May 2011; accepted 22 Jun 2011; published 1 Jul 2011 4 July 2011 / Vol 19, No S4 / OPTICS EXPRESS A994 internal quantum efficiency (IQE) in InGaN quantum wells (QWs) light-emitting diodes (LEDs) decreases significantly due to (1) high dislocation density results from the lattice mismatch between the sapphire substrate and GaN / InGaN leading to large non-radiative recombination rate, and (2) charge separation from the polarization fields in the QW leading to reduction of the electron-hole wavefunction overlap (Γe_hh) and radiative recombination rate (Rsp) in particular for green-emitting QWs
We investigated the approaches based on quantum well structures with large overlap design to enhance the internal quantum efficiency (IQE) for InGaN QWs based LEDs
The less-abrupt interface in staggered InGaN QWs due to the graded growth temperature approach will not affect the performance of the staggered InGaN QWs detrimentally
Summary
III-Nitride semiconductors have significant applications for solid state lighting and lasers [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20], power electronics [21], thermoelectricity [22,23], and solar cells [24,25,26]. Novel structures designed by employing thin large band gap barrier materials surrounding the InGaN QWs to suppress the efficiency droop are discussed The optimization of both radiative efficiency and current injection efficiency in InGaN QWs enables the realization of high internal quantum efficiency for nitride based LEDs emitting in the green wavelength region and longer.
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