Impact of dislocations and defects on the relaxation behavior of InGaN/GaN multiple quantum wells grown on Si and sapphire substrates

Abstract

We investigated the relaxation behavior of InGaN/GaN blue multiple quantum wells (MQWs) grown on Si (111) and sapphire (0001) substrates to determine how the threading dislocation density (TDD) in the underlying GaN layer, the thickness of the MQWs, and the growth substrate (Si or sapphire) affect the relaxation behavior of MQWs. The results demonstrate that the value of the in-plane lattice parameter difference between MQWs and GaN (IPLD MQWs-GaN ) is strongly dependent on the TDD in the underlying GaN layer. The thickness of the InGaN well layer has the greatest effect on the IPLD MQWs-GaN value of the blue MQW structure: a thin InGaN well layer with high In content is more effective than a thick InGaN well layer with low In content for obtaining highquality blue MQWs without misfit dislocations (MDs). Furthermore, MQWs grown on Si are likely to contain MDs and unlikely to form V-defects, whereas the opposite tendency is true of MQWs grown on sapphire. Using threading dislocations, MDs, and V-defects, we propose relaxation mechanisms for MQWs grown on Si (111) and sapphire (0001) substrates.

Carbon-nanotube-assisted nanoepitaxy of Si-doped GaN for improved performance of InGaN/GaN light-emitting diodes

“…While a number of studies corroborate the above conclusion [17,46], recent studies have determined that dislocations are also a source of the droop behavior by contributing to nonradiative carrier recombination at high injection currents [47,48]. In addition, these extended defects are known to affect the relaxation of MQWs [49] and carrier injection [50]. In light of the above considerations and from the observed reduction in the dislocation density and polarization effect in our device, the improved droop behavior is clearly a result of overall improvement in the device quality.…”

Reduction of basal plane defects in (11-22) semipolar InGaN/GaN MQWs fabricated on patterned (113) Si substrates by introducing AlGaN barrier layers

“…Prior to the MOCVD growth, patterning of Si substrates was performed. Stripe grooves with (111) Si facets extending along the direction were fabricated by a conventional photolithography technique. At first, a 100 nm‐thick thermally oxidized SiO 2 mask on (113) Si substrate was fabricated into a stripe pattern by ICP‐RIE.…”

“…These features enable drastic reduction in manufacturing costs. We have previously developed threading dislocation reduction and stress management techniques for GaN films grown on (111) Si substrates . As a result, extremely high efficient GaN‐based blue light‐emitting diodes (LEDs) on conventional (0001) plane have been achieved .…”

Efficiency and Forward Voltage of Blue and Green Lateral LEDs with V-shape defects and Random Alloy Fluctuation in Quantum Wells

“…Most V-defects are the result of dislocation lines that form under certain growth conditions. [10][11][12] Unlike the threading dislocation (TD) centers, which are typical nonradiative centers, the inclined sidewalls of V-defects reportedly assist carrier injection into QWs. [13][14][15] Given that V-defects play an important role in carrier injection, it is important to understand the role of random alloy fluctuations and of V-defects in carrier injection.…”