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The structural, elastic and electronic properties of Ti2SiN were studied by first-principle calculations. The calculated bond lengths of Ti-Si and Ti-C are 2.65 and 2.09 Å, respectively. The results show Ti2SiN is mechanically stable, and its bulk modulus B, shear modulus G, Young's modulus E, Poisson's ratio μ and anisotropy factor A are determined to be 182 GPa, 118 GPa, 291 GPa, 0.233 and 1.57, respectively. The calculated electronic structure indicates that Ti2SiN is anisotropic and conductive. 相似文献
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采用内收缩多参考组态相互作用(MRCI)方法, 结合价态范围内的最大相关一致基aug-cc-pV6Z, 计算了SiN自由基X2∑+, A2Π 和B2∑+电子态的势能曲线. 采用Davidson修正来避免由于MRCI方法本身的大小一致性缺陷产生的误差. 为了提高计算精度, 进一步考虑了相对论修正和核价相关修正对势能曲线的影响. 本文的相对论修正是利用二阶Douglas-Kroll 哈密顿近似在cc-pV5Z基组水平进行的; 同时核价相关修正是在cc-pCV5Z基组水平进行的. 对这些势能曲线进行拟合, 得到各种水平下三个电子态的光谱常数(Te, Re, ωe, ωexe, αe和Be), 并详细分析了Davidson修正、相对论修正和核价相关修正对光谱常数的影响. 与其他理论结果和实验数据进行比较, 可知本文的结果更精确、更完整. 相似文献
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High-frequency enhancement-mode millimeterwave AlGaN/GaN HEMT with an fT/fmax over 100 GHz/200 GHz
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Ultra-thin barrier (UTB) 4-nm-AlGaN/GaN normally-off high electron mobility transistors (HEMTs) having a high current gain cut-off frequency (fT) are demonstrated by the stress-engineered compressive SiN trench technology. The compressive in-situ SiN guarantees the UTB-AlGaN/GaN heterostructure can operate a high electron density of 1.27×1013cm-2, a high uniform sheet resistance of 312.8 Ω /□, but a negative threshold for the short-gate devices fabricated on it. With the lateral stress-engineering by full removing in-situ SiN in the 600-nm SiN trench, the short-gated (70 nm) devices obtain a threshold of 0.2 V, achieving the devices operating at enhancement-mode (E-mode). Meanwhile, the novel device also can operate a large current of 610 mA/mm and a high transconductance of 394 mS/mm for the E-mode devices. Most of all, a high fT/fmax of 128 GHz/255 GHz is obtained, which is the highest value among the reported E-mode AlGaN/GaN HEMTs. Besides, being together with the 211 GHz/346 GHz of fT/fmax for the D-mode HEMTs fabricated on the same materials, this design of E/D-mode with the realization of fmax over 200 GHz in this work is the first one that can be used in Q-band mixed-signal application with further optimization. And the minimized processing difference between the E- and D-mode designs the addition of the SiN trench, will promise an enormous competitive advantage in the fabricating costs. 相似文献
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本文研制了高性能的AlGaN/GaN高电子迁移率晶体管并进行了特性分析。诸如氮化铝插入层、氮化硅钝化、高宽窄比的T型栅、减小欧姆接触电阻和缩短漏源距离等技术被用于提高器件性能。使用半导体参数分析仪和矢量网络分析仪分别对前制器件的直流和交流特性进行了表征。所得80nm栅长的器件其最大漏极电流密度为1.41A/mm,该结果为到目前为止国内文献报道的最大值。同时测得峰值跨导为317mS/mm,特征频率为74.3GHz,最高振荡频率为112.4GHz。 相似文献
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Xin Jia Jun-jun Wei Yuechan Kong Cheng-ming Li Jinlong Liu Liangxian Chen Fangyuan Sun Xinwei Wang 《Surface and interface analysis : SIA》2019,51(7):783-790
The cooling behavior of GaN-on-diamond substrate can be enhanced by reducing the thermal boundary resistance (TBR), which is mainly determined by the nature of interlayer. Although SiN film is considered as the primary candidate of dielectric layer, it is still needed to be optimized. In order to facilitate the understanding of the influence of dielectric layer on the TBR of GaN-on-Diamond substrate, aluminum nitride (AlN), and silicon nitride (SiN) film were compared systematically, both of which are 100 nm. The time-domain thermoreflectance (TDTR) measurements, adhesion evaluation, and microstructural analysis methods were adopted to analyse these two interlayers. The results show the TBR of SiN interlayer is as low as 38.5 ± 2.4 m2K GW−1, comparing with the value of 56.4 ± 5.5 m2K GW−1 for AlN interlayer. The difference of TBR between these two interlayers is elucidated by the diamond nucleation density, and the adhesion between the diamond film and GaN substrate, both of which are affected by the surface charge and chemical groups of the dielectric layer. 相似文献