【Substrate Papers】Micro-segregation phenomena and related spectroscopic signals in melt-grown β-Ga₂O₃ single crystals

      Researchers from the Washington State University have published a dissertation titled " Micro-segregation phenomena and related spectroscopic signals in melt-grown β-Ga₂O₃ single crystals" in Journal of Applied Physic.

Abstract

      One of the primary advantages of β-Ga₂O₃ over incumbent wide bandgap semiconductors is the ability to grow directly from the melt. Melt growth, using Czochralski or similar methods, results in impurities in the crystal which originate from the crucible, such as iridium and other transition metals like chromium. These impurities exhibit optoelectronic signatures useful for their identification and sensitive to the Fermi energy of a given crystal (i.e., signatures vary with the electrical conductivity of the matrix). In this work, we describe how laser Raman systems can be used to map and spatially correlate Cr³⁺ photoluminescence, electronic-coupled Raman scattering from Ir⁴⁺ d–d internal transitions, and the Raman line attributed to hydrogenic shallow donors. Laser ablation inductively coupled plasma mass spectrometry directly measured spatially dependent relative metal concentrations and confirmed spectroscopic signals resulting from heterogeneities in impurity concentrations in β-Ga₂O₃ boules. Mapping of photoluminescence and Raman-related signatures is, thus, demonstrated as an effective and facile method for spatial measurement of chemical heterogeneities in both insulating and conductive melt-grown β-Ga₂O₃ crystals.

DOI:10.1063/5.0229858