[9p-PA3-1~18] 6.2 Carbon-based thin films

[9p-PA3-12] Visualization of crystal defects in diamond by two-photon-excited photoluminescence

〇Shinya Ohmagari¹, Hideaki Yamada¹, Nobuteru Tsubouchi¹, Hitoshi Umezawa¹, Akiyoshi Chayahara¹, Daisuke Takeuchi¹ (1.AIST ADPERC)

Keywords:diamond, dislocation, photoluminescence

Structural defects in diamond crystal can be evaluated by X-ray topography, cathode luminescence (CL), etch-pit method. However, these methods have poor resolution in the thickness direction (crystal growth direction) of the substrate, hence it is difficult to evaluate the three-dimensional propagation behavior of dislocations. In recent years, visualization of threading dislocations by two-photon absorption photoluminescence (2PPL) method has been reported in SiC, GaN. By evaluating the dark spot of band edge emission (caused by carrier recombination in the vicinity of dislocation), three-dimensional imaging of dislocation could observable. Since diamond has a much wider bandgap of 5.5 eV (225 nm), it is necessary to construct an optical system incorporating a short wavelength laser for band edge excitation. On the other hand, in diamond, since Band-A emission derived from dislocation is observed in the vicinity of 2.9 eV (430 nm), it is possible to directly excite the defect-related states by the 2PPL method. We have tried visualization of diamond crystal defects of mosaic wafer and heteroepitaxial substrate which possess relatively higher dislocation density 10⁶-10⁸ cm^-2 as an example.