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

Abstract

Highly-efficient GaN-based light-emitting diode (LED) wafers have been grown on La0.3Sr1.7AlTaO6 (LSAT) substrates by radio-frequency molecular beam epitaxy (RF-MBE) with optimized growth conditions. The structural properties, surface morphologies, and optoelectronic properties of as-prepared GaN-based LED wafers on LSAT substrates have been characterized in detail. The characterizations have revealed that the full-width at half-maximums (FWHMs) for X-ray rocking curves of GaN(0002) and GaN(10-12) are 190.1 and 210.2 arcsec, respectively, indicating that high crystalline quality GaN films have been obtained. The scanning electron microscopy and atomic force microscopy measurements have shown the very smooth p-GaN surface with the surface root-mean-square (RMS) roughness of 1.3 nm. The measurements of low-temperature and room-temperature photoluminescence help to calculate the internal quantum efficiency of 79.0%. The as-grown GaN-based LED wafers have been made into LED chips with the size of 300 × 300 μm2 by the standard process. The forward voltage, the light output power and the external quantum efficiency for LED chips are 19.6 W, 2.78 V, and 40.2%, respectively, at a current of 20 mA. These results reveal the high optoelectronic properties of GaN-based LEDs on LSAT substrates. This work brings up a broad future application of GaN-based devices.

Direct Observation of the Biaxial Stress Effect on Efficiency Droop in GaN-based Light-emitting Diode under Electrical Injection

“…Figure 3(b) shows the imaginary part of the dielectric function Im ( ε xx + ε yy ) that is proportional to the interband optical absorptions for the unpolarized light incident in the < 0001 > direction. The peak energies of the 1 h -1 e transition increase as the biaxial strain changes from compressive to tensile, which well agrees with the experimental blue shift result under the current injection 29 30 31 . As shown in Fig.…”

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures

“…6a shows the GaN(10 5) RSM of ~300 nm-thick GaN films grown at 750 °C, from which the lattice parameters for GaN films are measured to be a = 0.32313 nm and c = 0.51792 nm 2 35 . These results reveal that as-grown ~300 nm-thick GaN films at 750 °C are about 0.13% tensile along their a axis and about 1.31% compressive along their c axis, because the lattice parameters for fully relaxed GaN are a = 0.31895 nm and c = 0.51860 nm 2 35 36 37 . The strain state for GaN films grown with various temperatures is also studied, as shown in Fig.…”

One-Step Fabrication Method of GaN Films for Internal Quantum Efficiency Enhancement and Their Ultrafast Mechanism Investigation

“…As a third-generation semiconductor, gallium nitride (GaN) has attracted considerable research interest because of its widespread applications in light-emitting diodes (LEDs), ultraviolet (UV) detectors, visible light communication, single-photon emission, microelectromechanical devices, , etc. The great potential of GaN is attributed to its excellent physical and chemical properties, especially wide direct band gap, high thermal conductivity, high chemical stability, and high electron mobility. − In recent years, the research on GaN-based LEDs with UV emission has been a research hotspot because of their excellent performance. − For instance, the UV light emission efficiency of GaN-based LEDs can increase significantly by nanowire array or quantum dot growth. − Also, graphene oxide passivation on top of the fully GaN-based LEDs is also a good method for suppressing spontaneous polarization to augment the light output of UV-LEDs . These studies were conducted by means of chemical growth or synthesis, which needs complex procedures and a rigorous experimental environment.…”