Comprehensive model toward optimization of SAG In-rich InGaN nanorods by hydride vapor phase epitaxy

Abstract

Controlled growth of In-rich InGaN nanowires/nanorods (NRs) has long been considered as a very challenging task. Here, we present the first attempt to fabricate InGaN NRs by selective area growth using hydride vapor phase epitaxy. It is shown that InGaN NRs with different indium contents up to 90% can be grown by varying the In/Ga flow ratio. Furthermore, nanowires are observed on the surface of the grown NRs with a density that is proportional to the Ga content. The impact of varying the NH3 partial pressure is investigated to suppress the growth of these nanowires. It is shown that the nanowire density is considerably reduced by increasing the NH3 content in the vapor phase. We attribute the emergence of the nanowires to the final step of growth occurring after stopping the NH3 flow and cooling down the substrate. This is supported by a theoretical model based on the calculation of the supersaturation of the ternary InGaN alloy in interaction with the vapor phase as a function of different parameters assessed at the end of growth. It is shown that the decomposition of the InGaN solid alloy indeed becomes favorable below a critical value of the NH3 partial pressure. The time needed to reach this value increases with increasing the input flow of NH3, and therefore the alloy decomposition leading to the formation of nanowires becomes less effective. These results should be useful for fundamental understanding of the growth of InGaN nanostructures and may help to control their morphology and chemical composition required for device applications.

Circumventing the ammonia-related growth suppression for obtaining regular GaN nanowires by HVPE

“…In our previous work, we have shown that the optimal deposition temperature for SAG of GaN by HVPE is 980 °C [23,25]. A temperature range of 880 °C-980 °C was used in this study.…”

Особенности зарождения и роста нитевидных нанокристаллов InGaN на подложках SiC/Si методом хлорид-гидридной эпитаксии

“…Прежде всего это связано со сложностью получения низкодефектных пленок InGaN. Для решения данной проблемы авторы ряда работ [1][2][3] предлагают при создании гетероструктур вместо эпитаксиальных сплошных слоев, содержащих индий, использовать нитевидные нанокристаллы (ННК), поскольку в самих нанокристаллах практически не образуются дислокации несоответствия [4]. Отметим, что основная часть работ посвящена росту методами молекулярно-пучковой эпитаксии или газофазной эпитаксии из металлоорганических соединений.…”