Luminescence Studies of Oxygen‐Related Defects In Aluminum Nitride

Abstract

Aluminum nitride possesses a unique ability to accommodate oxygen via lattice dissolution to levels exceeding 4 at.%. The mechanism for this large accommodation of oxygen is of technological and scientific interest due to the established deleterious effects of oxygen on the thermal conductivity in this material. When doped with oxygen, AIN exhibits an intense, very broad (FWHM > 1 eV), luminescence peak in the near-UV (-375 nm). Though there is little doubt that this transition is associated with oxygen incorporation in the lattice, both the anomalous width of this feature and the specific complex from which it is derived have been a matter of debate. This paper reviews past studies of the luminescence of oxygen-related defects in AIN and presents recent detailed photoluminescence experiments which delineate changes in the luminescence as a function of oxygen content. These data are utilized in conjunction with other measurements to elucidate the nature of the oxygen-related defect and its evolution as a function of oxygen concentration. A defect-cluster model is presented which accounts for a transition in the luminescent properties of AIN and is found to be in accord with measurements on thermal conduction and unit-cell volume changes in AIN. This understanding of the oxygen-related defect in AIN from the photoluminescence studies is then utilized in cathodoluminescence studies via cathodoluminescence imaging in a scanning electron microscope and a transmission electron microscope. Such techniques are extremely useful in elucidating the distribution and interaction of oxygen in the microstructure of sintered AIN ceramics, which has been heretofore an extremely difficult problem in microstructural and microchemical analysis of such sintered ceramics. [

Depth-dependent investigation of defects and impurity doping in GaN/sapphire using scanning electron microscopy and cathodoluminescence spectroscopy

“…We argue that this peak may be due to Al-N-O complexes, since 3.8 eV emission in AlN has been assigned to O impurities. 17 A similar broad emission above band edge with different energy was observed in sample C, which will be discussed later. The broad 2.9 eV BL intensity is negligible within the Al 2 O 3 or the bulk GaN but is observed for d int Ͻ0.2 m. Unlike the 2.9 eV emission commonly reported for heavily Mg-doped p-type GaN, ours appears in an n-type sample.…”

Enhanced Polarization in Tadpole-Shaped (Ni, Al)/Aln Nanoparticles and Microwave Absorption at High Frequencies

“…It is can be seen a broad UV-blue emission band centered at 350 nm (i. [22]. Hence, the luminescence at 350 nm of our (Ni, Al)/AlN nanoparticles originates from the co-work of oxygen-related defect and Al vacancy in weakly oxided aluminum nitrides, while we cannot find any PL response in the (Ni, Al)/Al 2 O 3 nanoparticles.…”

Drop and recovery of thermal conductivity of AlN upon UV irradiation

“…In this work, we provide a theoretical support for the simple model suggested by Harris et al [9] through theortical estimates (based upon more accurate and detailed theory) of the role of oxygen-related defects in AlN in the forms of both point impurities and extended defect complexes (clusters as reported in Ref. [2]). …”

“…It is believed that oxygen incorporation generates Al vacancies and oxygen substitution at N sites. For example, it has been proposed that at oxygen concentration below 0.75 at.%, every Al vacancy (V Al ) is surrounded by three substituted oxygen atoms (O N ), and above 0.75 at.% a V Al is surrounded by an octahedrally bonded O N configuration [2]. Theoretical investigations suggest that oxygen-related defects produce electronic states which lie deep in the band gap of bulk AlN [4,12].…”

“…AlN has the ability to accommodate oxygen to levels exceeding 4 at.%. Due to the effect of oxygen on the thermal conductivity of AlN, the mechanism of the large accommodation of oxygen is of high sceintific and technological interest [2]. However, the local atomic structure of the oxygen point defects in AlN is still a controvercial issue [3].…”