Performance improvement of GaN-based LEDs with step stage InGaN/GaN strain relief layers in GaN-based blue LEDs.

The performance of nitride-based LEDs was improved by inserting dual stage and step stage InGaN/GaN strain relief layer (SRL) between the active layer and n-GaN template. The influences of step stage InGaN/GaN SRL on the structure, electrical and optical characteristics of GaN-based LEDs were investigated. The analysis of strain effect on recombination rate based k·p method indicated 12.

[Optical characteristics of InGaN/GaN light emitting diodes on patterned sapphire substrate].

In the present paper, optical characteristics of InGaN/GaN multiple quantum wells light emitting diodes fabricated on the conventional (C-LEDs) and patterned sapphire substrates (PSSLEDs) were investigated by electroluminescence (EL) and photoluminescence (PL). PSSLEDs show higher light output power and smaller full width at half maximum (FWHM) of EL than those of C-LEDs for their better crystalline quality. The FWHM of EL for PSSLEDs exhibits faster broadening as current increases than C-LEDs, while the same broadening of FWHM of PL as excitation power increases is shown in PSSLEDs and C-LEDs, which indicate that there is stronger band filling effect in PSSLEDs caused by relatively higher carrier density in their QWs at the same current injection level.