Quasiregular quantum-dot-like structure formation with postgrowth thermal annealing of InGaN/GaN quantum wells

Abstract

Postgrowth thermal annealing of an InGaN/GaN quantum-well sample with a medium level of nominal indium content ͑19%͒ was conducted. From the analyses of high-resolution transmission electron microscopy and energy filter transmission electron microscopy, it was found that thermal annealing at 900 °C led to a quasiregular quantum-dot-like structure. However, such a structure was destroyed when the annealing temperature was raised to 950 °C. Temperature-dependent photoluminescence ͑PL͒ measurements showed quite consistent results. Blueshift of the PL peak position and narrowing of the PL spectral width after thermal annealing were observed.

Improvement of green LED by growing p-GaN on In0.25GaN/GaN MQWs at low temperature

“…5(a). Several studies have reported that the indium composition in InGaN/GaN MQWs changed as a result of thermal annealing [23], and the thickness of the quantum wells and barriers is also influenced by a hightemperature heat treatment [24]. Moreover, the line-width narrowing was observed due to the enhanced interdiffusion between the dot-like structures and the surrounding indium-deficient matrices by thermal annealing [25].…”

Depth dependence of optical property beyond the critical thickness of an InGaN film

“…To release strain energy, indium aggregation and phase separation can usually result in nano-scale indium-rich clusters and compositional fluctuations [4][5][6]. In particular, when a perturbation is introduced, such as thermal annealing, spinodal decomposition will enhance the clustering process [7,8]. Besides the local aggregation phenomenon, a more global behavior, called indium pulling [9][10][11], was also discovered.…”

A comparative analysis of the photoluminescence spectra of annealed ultrasmall In-rich InGaN/GaN quantum dots and wells

“…This may also lead to In-clustering and dots may be formed instead of a QW [6,7]. In spite of these problems the growth of ultrathin In-rich (UTIR) InXGa1−XN/GaN QWs having In composition of 60% -70% have been reported [8].…”

“…The results obtained are shown in Figs.3 -5. As depicted in these figures, for UTIR QWs the indium7 mole fraction corresponds to the as-grown indium concentration in InXGa1-XN layer, while in the case of dots it corresponds to the initial core concentration.Fig. 3shows the variation of the PL peak energies of as-grown and long annealed nanostructures (UTIR QWs and USIR QDs) with the BP for different indium concentrations corresponding to EC : EV = 83:17 and 68:32.…”