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Spin Phenomena of CdZnSe Self-assembled Quantum Dots Investigated by Magneto-photoluminescence
Yungjun Kim,M. Dobrowolska,J. K. Furdyna,이상훈 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1
Magneto-photoluminescence (PL) experiments were carried out on a self-assembled CdZnSe/ZnSe quantum dot (QD) system. The intensities of the PL peak exhibited significant differences for the two circular polarizations when a magnetic field was applied. A simple two-level rate equation model, including the spin flip time τs and the exciton recombination time τr , was used to analyze the observed degree of the polarization in the polarization selective PL measurements. Specifically, the magnetic field dependence of the polarization was fitted by treating τs/τr as a fitting parameter in the model. The best fitting was obtained with the value of τs/τr ~ σ, indicating that the spin relaxation time is much longer than the exciton recombination time. Such polarization selective PL measurements were further performed at several different temperatures, which showed a systematic decrease in the degree of polarization with increasing temperature. Magneto-photoluminescence (PL) experiments were carried out on a self-assembled CdZnSe/ZnSe quantum dot (QD) system. The intensities of the PL peak exhibited significant differences for the two circular polarizations when a magnetic field was applied. A simple two-level rate equation model, including the spin flip time τs and the exciton recombination time τr , was used to analyze the observed degree of the polarization in the polarization selective PL measurements. Specifically, the magnetic field dependence of the polarization was fitted by treating τs/τr as a fitting parameter in the model. The best fitting was obtained with the value of τs/τr ~ σ, indicating that the spin relaxation time is much longer than the exciton recombination time. Such polarization selective PL measurements were further performed at several different temperatures, which showed a systematic decrease in the degree of polarization with increasing temperature.
Analysis of Cell Current with Abnormal Channel Profile in 3D NAND Flash Memory
Jaewoo Lee,Yungjun Kim,Yoocheol Shin,Seongjo Park,Daewoong Kang,Myounggon Kang 대한전자공학회 2024 Journal of semiconductor technology and science Vol.24 No.2
This letter presents an in-depth investigation of the channel profile and cell current analysis of abnormal vertical 3D NAND flash memory. By utilizing 3D (technology computer-aided design) TCAD simulation, the channel profile was designed with an oxide-nitride-oxide (O/N/O) structure, providing insights into its impact on device performance. The ID-VDS curve was measured after setting the Vth target in the program state, enabling the analysis of the cell current. Additionally, the E-field of the tunneling oxide was considered to gain a comprehensive understanding of the device behavior. Based on the analysis results, the structure most vulnerable to cell current in vertical 3D NAND flash memory has been identified.