Enhancement of nonvolatile memory characteristics caused by GaN/AlN resonant tunneling diodes
Enhancement of nonvolatile memory characteristics caused by GaN/AlN resonant tunneling diodes
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DOI：
10.1088/1361-6641/acbaf8
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发表时间：
2023-02
影响因子：
1.9
通讯作者：
M. Nagase;Tokio Takahashi;M. Shimizu
中科院分区：
文献类型：
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作者：
M. Nagase;Tokio Takahashi;M. Shimizu
报道了一种通过减少量子阱结构中的晶体缺陷来增强GaN/AlN共振隧穿二极管(RTD)的非易失性存储特性的方法。当采用纯氮气作为载气，而不是氮气/氢气混合物，并引入三甲基氯化钠作为金属有机气相外延量子阱结构的表面活性剂时，凹坑状晶体缺陷得到了强烈的抑制。此外，通过控制GaN/AlN RTD和蓝宝石(0001)衬底之间缓冲层的生长条件和结构，降低了位错密度。通过量子阱结构的泄漏电流降低，并导致了极高的开关>；1300，这比以前的研究得到的值高出20倍。基于泊松方程和Tsu-Esaki公式的理论计算表明，将量子阱中积累的电子密度增加到1018 cm-3量级，可以提高>；103的高开关比。此外，通过以快于晶体缺陷释放电子的速度的纳秒时间尺度输入顺序脉冲电压来执行非易失性存储操作。这些结果有力地表明，GaN/AlN RTD的非挥发性存储特性是由于量子阱中的子带间跃迁和电子积累所致，而不是由于晶体缺陷对电子的俘获。
This paper reports an enhancement of the nonvolatile memory characteristics of GaN/AlN resonant tunneling diodes (RTDs) by reducing the crystal defects in the quantum well structure. Pit-shaped crystal defects are strongly suppressed when pure N2, instead of a N2/H2 mixture, is used as a carrier gas and trimethylindium is introduced as a surfactant for metalorganic vapor phase epitaxy of the quantum well structure. In addition, the density of dislocations is lowered by controlling the growth conditions and structure of the buffer layer between a GaN/AlN RTD and a sapphire (0001) substrate. The leakage current through the quantum well structure is lowered, and an extremely high ON/OFF of >1300, which is 20 times higher than the values obtained in previous studies, is induced. Theoretical calculations based on Poisson’s equation and the Tsu–Esaki formula indicate that a high ON/OFF ratio of >103 can be enhanced by increasing the density of electrons accumulating in the quantum well to a level on the order of 1018 cm–3. Furthermore, nonvolatile memory operations were performed by inputting the sequential pulse voltages with a speed of nanosecond time scale which is faster than speeds of electron releases from the crystal defects. These results strongly indicate that the nonvolatile memory characteristics of GaN/AlN RTDs are due to intersubband transitions and electron accumulation in the quantum well and are not attributed to electron trapping by the crystal defects.