C, O, Si Impurities in PVT-AlN – Incorporation and measurement by SIMS/Absorption

• Applicant: Andrew Klump, Ph.D.
• Subject Area: Synthesis and Properties of Functional Materials ; Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 503007402

One of the key limitations to the efficiency of ultraviolet light-emitting diodes is the lack of a suitable substrate as a base for growing the device. Aluminum nitride (AlN) could solve this problem - except for the absorption of light near the operating wavelength of these devices. Prior work has suggested that the ratio of the C, O, and Si impurities in the substrates are the primary influence on this absorption, yet there is a fundamental lack of understanding of how these defects are entering the crystal. In addition, the measurement of the concentrations of impurities is not trivial - due to cost, and difficulty of the measurement technique.The purpose of this project, therefore, is to investigate the ultraviolet wavelength absorption of AlN as a function of the C, O, and Si content. This will require (1) the current concentration measurement be improved, and cross-calibrating it to a secondary technique so that every sample can be measured and analyzed. (2) The pathway for C, O, and Si to be unintentionally incorporated needs to be understood, and their concentrations be reduced. (3) Once the unintended concentrations reach a minimum, a growth process to achieve precise concentrations of the elements will be developed. (4) Finally, a series of AlN samples with varying ratios of the elements will be generated, and measured with absorption spectroscopy. The appearance, shape, and intensity of absorption peaks from the visible wavelengths to the ultraviolet will be compared, so that rules correlating the concentrations and the ultraviolet absorption can be established.

• DFG Programme: WBP Position