10:45 〜 11:00
▲ [15a-513-7] Cathodoluminescence Characterization of Mix and Edge Dislocations in etched GaN
キーワード：Semiconductor, GaN, Dislocation
Recently, GaN has attracted much interest for power device application since it has a large band gap and high thermal stability. Due to detriment of device performance by high dislocation density, it is necessary to grow high quality GaN wafer with low dislocation density for the application of Mega Watts power device. The characterization of threading dislocations could contribute to the failure analysis of device performance.
In this study, we have applied chemical etching by molten KOH+Na2O2 solution [1] and cathodoluminescence (CL) to distinguish dislocations and investigate their character. Fig 1 (a) shows mix type (screw + edge) dislocation with a hole in the center of etch pit and edge dislocation without a hole. The CL spectral line profile taken at 20 K clearly shows that for mix type dislocation DAP emission intensity in the center position is higher than the others, while for edge dislocation that is the same for all positions, as shown in fig 1 (b) to (e). For near band edge (NBE) emission, the CL intensities in both mix and edge center are lower than the others. A red-shift around 5.1 meV for mix dislocation was observed while no shift for edge dislocation. The enhanced DAP emission and red-shift of NBE emission of mix dislocation vanish after the etch pit pattern is removed by cross section polisher. It is concluded that the enhanced DAP emission and red-shift of mix dislocation result from the chemical etching. Three reasons, including H or O incorporation, and strain relaxation acting through deformation potential stemming from a etch pit hole, will be discussed.
Acknowledgements:This work was supported by “Next-generation semiconductor research and development to contribute to energy-saving social realization” project under the Ministry of Education, Culture, Sports, Science and Technology.
In this study, we have applied chemical etching by molten KOH+Na2O2 solution [1] and cathodoluminescence (CL) to distinguish dislocations and investigate their character. Fig 1 (a) shows mix type (screw + edge) dislocation with a hole in the center of etch pit and edge dislocation without a hole. The CL spectral line profile taken at 20 K clearly shows that for mix type dislocation DAP emission intensity in the center position is higher than the others, while for edge dislocation that is the same for all positions, as shown in fig 1 (b) to (e). For near band edge (NBE) emission, the CL intensities in both mix and edge center are lower than the others. A red-shift around 5.1 meV for mix dislocation was observed while no shift for edge dislocation. The enhanced DAP emission and red-shift of NBE emission of mix dislocation vanish after the etch pit pattern is removed by cross section polisher. It is concluded that the enhanced DAP emission and red-shift of mix dislocation result from the chemical etching. Three reasons, including H or O incorporation, and strain relaxation acting through deformation potential stemming from a etch pit hole, will be discussed.
Acknowledgements:This work was supported by “Next-generation semiconductor research and development to contribute to energy-saving social realization” project under the Ministry of Education, Culture, Sports, Science and Technology.