Carrier capture by threading dislocations in (In,Ga)N/GaN heteroepitaxial layers

Abstract

Using spatially resolved cathodoluminescence spectroscopy, we investigate the spatial luminescence distribution in a fully strained ͑In,Ga͒N layer, in particular, its correlation with the distribution of threading dislocations ͑TDs͒. Regarding the impact of TDs on the luminescence properties, we can clearly distinguish between pure edge-type TDs and TDs with screw component. At the positions of both types of TDs, we establish nonradiative recombination sinks. The radius for carrier capture is at least four times larger for TDs with screw component as for pure edge-type TDs. The large capture radius of the former is due to a spiral-like growth mode resulting in an increase in the In content in the center of the spiral domains in comparison to their periphery.

Influence of V-pits on the efficiency droop in InGaN/GaN quantum wells

“…2(b) and 2(d)) show the large (small) V-pit in the physical domain and its schematic energy diagram with carrier recombination process, respectively. Figure 2(c) shows that the presence of V-pits at the entire part of low In SLs effectively suppresses the lateral diffusion into TDs, minimizing the dark spot sizes [22]. On the other hand, as shown in Fig.…”

“…1(d). The lateral sizes of dark spots by small V-pits become much larger than their physical sizes, suggesting that the non-radiative recombination domains are extended even outside V-pits [22]. This should be understood by the lateral diffusion of carriers and formation of TDs without the facets as below.…”

“…1 (a) and (b) that the dark spots or non-radiative recombination areas coincide with the locations of V-pits. In optical characterization using CL, the bright region represents the higher intensity of cathodoluminescence throughout the radiative recombination of electrons and holes excited by the accelerated electrons [22,23]. Inset in Fig.…”

Surface scattering velocities in III-nitride quantum well laser structures via the emission of hybrid phonons

“…Due to their large energy gaps, III-nitride materials can be used for emitters which are active in the blue/green and ultraviolet region as well. In recent years, several techniques have been employed to fabricate high quality QW heterostructures [1][2][3][13][14] and experimental results have been reported concerning the ability of QWs for lasing [10][11][12].…”

“…During the last decades, semiconductor industry has focused its interest on growth QW lasers structures made, among others, with III-nitride materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Low dimensional structures (LDS) based on nitride semiconductor materials have been used for fabricating light emitting diodes.…”