Investigation of Micromorphology and Carrier Recombination Dynamics for InGaN/GaN Multi-Quantum Dots Grown by Molecular Beam Epitaxy

Abstract

InGaN quantum dots (QDs) are promising candidates for GaN-based all-visible optoelectronic devices such as micro light-emitting diode and laser. In this study, self-assembled InGaN/GaN multi-quantum dots (MQDs) have been grown by plasma-assisted molecular beam epitaxy on c-plane GaN-on-sapphire template. A high density of over 3.8 × 1010 cm−2 is achieved and InGaN QDs exhibit a relatively uniform size distribution and good dispersity. Strong localization effect in as-grown InGaN QDs has been evidenced by temperature-dependent photoluminescence (PL). The variation of peak energy is as small as 35 meV with increasing temperature from 10 K to 300 K, implying excellent temperature stability of emission wavelength for InGaN MQDs. Moreover, the radiative and nonradiative recombination times were calculated by time-resolved PL (TRPL) measurements, and the temperature dependence of PL decay times reveal that radiative recombination dominates the recombination process due to the low dislocation density of QDs structure.

Droplet epitaxy of InGaN quantum dots on Si (111) by plasma-assisted molecular beam epitaxy

“…After the pre-nitridation process in Fig. 1 b, the streaky RHEED pattern with Kikuchi lines indicates the flat surface formed with a crystalline structure [ 10 , 14 , 25 ]. A very thin SiN x layer was formed because nitrogen atoms absorbed on the Si surface, which will also be reported by the observation of HR-TEM.…”

“…The higher growth temperature increased the average diameter of InGaN QDs from 13.3 ± 3.0 to 28.7 ± 13.2 nm, and the dot density decreased dramatically from 1.33 × 10 11 to 1.66 × 10 10 cm −2 . These can be attributed to the improved migration length and aggregation of adatoms to form bigger dots at higher growth substrate temperatures [ 14 ]. The evaporation of indium from the substrate at higher growth temperature also occurred during the growth, which could significantly decrease the dot density.…”

“…For instance, InGaN quantum dots (QDs) have excellent characteristics for optoelectronic devices, such as light emitting diodes (LEDs) [ 1 – 3 ], infrared photodetectors [ 4 – 6 ], and laser diodes [ 7 – 9 ]. The most commonly used mechanism for the growth of self-assembly QDs is Stranski–Krastanov (SK) mode [ 10 – 12 ] through molecular beam epitaxy (MBE) [ 13 , 14 ] and metal–organic chemical deposition (MOCVD) [ 15 – 17 ]. However, the SK mode has drawbacks as the growth of InGaN QDs triggered by layer strain, which can produce threading dislocations or defects, and uncontrollable density [ 10 , 18 ].…”

Structural and optical analyses for InGaN-based red micro-LED

“…In contrast to the S-shaped temperature-dependent behavior, we did not observe any redshift in our experiment at low temperatures. This suggests that carriers are strongly localized due to the localized states in red QWs with high In content [50][51][52].…”

Enhanced Properties of Extended Wavelength InGaAs on Compositionally Undulating Step-Graded InAsP Buffers Grown by Molecular Beam Epitaxy

“…As can also be seen from Figure 6b, the overall intensity of the PL spectra diminishes significantly as temperature increases, which is due to the thermal quenching effect caused by phonon-assisted non-radiative recombination. In order to further understand the mechanism of carrier thermal quenching in the InGaAs layer, Arrhenius-like expression given in Equation ( 4) is applied to fit the experimental data of the PL intensity [31,32], in which two non-radiative recombination processes are assumed.…”