Evolution of impurity incorporation during ammonothermal growth of GaN

Sakari Sintonen*, Stefanie Wahl, Susanne Richter, Sylke Meyer, Sami Suihkonen, Tobias Schulz, Klaus Irmscher, Andreas N. Danilewsky, Turkka Tuomi, Romuald Stankiewicz, Martin Albrecht

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    14 Citations (Scopus)


    Ammonothermally grown GaN is a promising substrate for high-power optoelectronics and electronics thanks to its scalability and high structural perfection. Despite extensive research, ammonothermal GaN still suffers from significant concentrations of impurities. This article discusses the evolution of impurity incorporation during growth of basic ammonothermal GaN, in specific whether the impurity concentration changes temporally along the growth direction and how the autoclave influences the impurity concentration. The effect of the impurities on the structural, electrical and optical properties of the grown crystal is also discussed. The chemical analysis is carried out by time of flight secondary ion mass spectroscopy (ToF-SIMS) and laser-ablation inductively-coupled plasma mass spectroscopy (LA-ICP-MS). Strain and dislocation generation caused by impurity concentration gradients and steps are studied by synchrotron radiation x-ray topography (SR-XRT). Fourier transform infrared (FTIR) reflectivity is used to determine the effect of the impurities on the free carrier concentration, and the luminescent properties are studied by low temperature photoluminescence (PL). The influence of the autoclave is studied by growing a single boule in multiple steps in several autoclaves. LA-ICP-MS and ToF-SIMS ion intensities indicate that the impurity concentrations of several species vary between different autoclaves by over an order of magnitude. SR-XRT measurements reveal strain at the growth interfaces due to impurity concentration gradients and steps. Oxygen is determined to be the most abundant impurity species, resulting in a high free carrier concentration, as determined by FTIR. The large variation in Mn concentration dramatically affects PL intensity.

    Original languageEnglish
    Pages (from-to)51-57
    Number of pages7
    JournalJournal of Crystal Growth
    Publication statusPublished - 15 Dec 2016
    MoE publication typeA1 Journal article-refereed


    • A1. Impurities
    • A2. Ammonothermal crystal growth
    • A2. Single crystal growth
    • B1. Bulk GaN
    • B1. Nitrides


    Dive into the research topics of 'Evolution of impurity incorporation during ammonothermal growth of GaN'. Together they form a unique fingerprint.

    Cite this