Efficiency measurement of GaN-based quantum well and light-emitting diode structures grown on silicon substrates

Abstract

The optical efficiency of GaN-based multiple quantum well (MQW) and light emitting diode (LED) structures grown on Si(111) substrates by metal-organic vapor phase epitaxy was measured and compared with equivalent structures on sapphire. The crystalline quality of the LED structures was comprehensively characterized using x-ray diffraction, atomic force microscopy, and plan-view transmission electron microscopy. A room temperature photoluminescence (PL) internal quantum efficiency (IQE) as high as 58% has been achieved in an InGaN/GaN MQW on Si, emitting at 460 nm. This is the highest reported PL-IQE of a c-plane GaN-based MQW on Si, and the radiative efficiency of this sample compares well with similar structures grown on sapphire. Processed LED devices on Si also show good electroluminescence (EL) performance, including a forward bias voltage of ∼3.5 V at 20 mA and a light output power of 1 mW at 45 mA from a 500×500 μm2 planar device without the use of any additional techniques to enhance the output coupling. The extraction efficiency of the LED devices was calculated, and the EL-IQE was then estimated to have a maximum value of 33% at a current density of 4 A cm−2, dropping to 30% at a current density of 40 A cm−2 for a planar LED device on Si emitting at 455 nm. The EL-IQE was clearly observed to increase as the structural quality of the material increased for devices on both sapphire and Si substrates.

Monolithically Integrated μLEDs on Silicon Neural Probes for High-Resolution Optogenetic Studies in Behaving Animals

“…As a result, the internal quantum efficiency (IQE) of the μLED is limited: only approximately 33% of the injected carriers can produce photons (Zhu et al, 2011). These photons generated at the active region are emitted in all directions.…”

Highly-efficient GaN-based light-emitting diode wafers on La0.3Sr1.7AlTaO6 substrates

“…Actually, there is a ~1.5 nm blue shift in PL peak conducted at LT when compared with that at RT. This is attributed to the fact that there are high-energy carriers existing at low temperature, which lead to the low wavelength during the radiative recombination293031323345. It is widely accepted that the IQE can be estimated as the ratio of the peak PL intensities I RT at RT and I LT at LT, where the LT IQE is assumed to be 100%46.…”

Correlation on GaN epilayer quality and strain in GaN-based LEDs grown on 4-in. Si(1 1 1) substrate

“…The full width at half maximum (FWHM) of (0002) are 1153.2, 904.7, and 631.5 arcsec, while those of (10-12) are 1766.7, 1690.7, and 1604 arcsec for samples A, B and C, respectively. For sample C, the screw component TDs density is calculated the above corresponding FWHM value[24], which is lower by one order of magnitude than our previous results[13], and the same order as compared with the other groups[25][26]. It can be concluded that there is a significant improvement of GaN epilayer quality when increasing the thickness of n-GaN.…”