A physics-based analytical expression that predicts the charge, electrical field and potential distributions along the gated region of the GaN HEMT channel has been developed. Unlike the gradual channel approximation (GCA), the proposed model considers the non-uniform variation of the concentration under the gated region as a function of terminal applied voltages. In addition, the model can capture the influence of mobility and channel temperature on the charge distribution trend. The comparison with the hydrodynamic (HD) numerical simulation showed a high agreement of the proposed model with numerical data for different bias conditions considering the self-heating and quantization of the electron concentration. The analytical nature of the model allows us to reduce the computational and time cost of the simulation. Also, it can be used as a core expression to develop a complete physics-based transistor Ⅳ model without GCA limitation.

In this work, the GaN p-MISFET with LPCVD-SiN_x is studied as a gate dielectric to improve device performance. By changing the Si/N stoichiometry of SiN_x, it is found that the channel hole mobility can be effectively enhanced with Si-rich SiN_x gate dielectric, which leads to a respectably improved drive current of GaN p-FET. The record high channel mobility of 19.4 cm²/(V?s) was achieved in the device featuring an Enhancement-mode channel. Benefiting from the significantly improved channel mobility, the fabricated E-mode GaN p-MISFET is capable of delivering a decent-high current of 1.6 mA/mm, while simultaneously featuring a negative threshold-voltage (V_TH) of –2.3 V (defining at a stringent criteria of 10 μA/mm). The device also exhibits a well pinch-off at 0 V with low leakage current of 1 nA/mm. This suggests that a decent E-mode operation of the fabricated p-FET is obtained. In addition, the V_TH shows excellent stability, while the threshold-voltage hysteresis ΔV_TH is as small as 0.1 V for a gate voltage swing up to –10 V, which is among the best results reported in the literature. The results indicate that optimizing the Si/N stoichiometry of LPCVD-SiN_x is a promising approach to improve the device performance of GaN p-MISFET.

本文采用金属有机化学气相沉积（MOCVD）生长原位SiNx栅介质制备了用于Ka波段高功率毫米波应用的AlN/GaN金属绝缘体半导体高电子迁移率晶体管（MIS-HEMTs）。原位生长SiN_x栅介质显著抑制了栅反向漏电、栅介质/AlN界面态密度和电流坍塌。所研制的MIS HEMTs在V_GS= 2 V时最大饱和输出电流为2.2 A/mm，峰值跨导为509 mS/mm，在V_GS = -30 V时肖特基栅漏电流为4.7×10^-6 A/mm。采用0.15 μmT形栅技术，获得98 GHz的f_T和165 GHz的f_MAX。大信号测量表明，在连续波模式下，漏极电压V_DS = 8 V时，MIS HEMT在40 GHz下输出功率密度2.3 W/mm，45.2%的功率附加效率（PAE），而当V_DS增加到15 V时，功率密度提升到5.2 W/mm，PAE为42.2%。

本文采用等离子体增强原子层沉积（PEALD）生长的SiN_x栅介质制备了宽带应用的AlGaN/GaN金属绝缘体半导体高电子迁移率晶体管（MIS-HEMTs），并在直流、小信号及大信号测试中评估了该介质层对器件性能的提升。测试结果表明改进器件具有高质量界面、宽栅极控制范围、良好的电流崩塌控制等优势，并确认了其在超过5 GHz下工作时仍能保持较高的功率附加效率（PAE）。在5 GHz连续波模式下，漏极电压V_DS = 10 V时，MIS HEMT输出功率密度为1.4 W/mm，PAE可达到74.7%；V_DS增加到30 V时，功率密度提升到5.9 W/mm，PAE可保持在63.2%的水平；测试频率增加30 GHz，在相同的输出功率水平下，器件的PAE达到50.4%。同时，高质量栅极介电层还可允许器件承受高的栅极电压摆动：在功率增益压缩6 dB时，栅极电流保持在10^-4 A/mm。上述结果证实了该SiN_x栅介质对器件性能的提升，使其满足宽带应用的高效率、高功率和可靠性要求，为系统和电路的宽带设计提供器件级的保障。

Amorphous oxide semiconductors (AOS) have unique advantages in transparent and flexible thin film transistors (TFTs) applications, compared to low-temperature polycrystalline-Si (LTPS). However, intrinsic AOS TFTs are difficult to obtain field-effect mobility (μ_FE) higher than LTPS (100 cm²/(V·s)). Here, we design ZnAlSnO (ZATO) homojunction structure TFTs to obtainμ_FE = 113.8 cm²/(V·s). The device demonstrates optimized comprehensive electrical properties with an off-current of about 1.5 × 10^–11 A, a threshold voltage of –1.71 V, and a subthreshold swing of 0.372 V/dec. There are two kinds of gradient coupled in the homojunction active layer, which are micro-crystallization and carrier suppressor concentration gradient distribution so that the device can reduce off-current and shift the threshold voltage positively while maintaining high field-effect mobility. Our research in the homojunction active layer points to a promising direction for obtaining excellent-performance AOS TFTs.

有机电致发光（OLED）是目前最有竞争力的显示技术，市场占有量逐年攀升。高效、稳定的OLED，特别是深蓝光器件，性能仍需提升，其关键问题是高性能的电子传输材料的研发。这是由于有机分子难以获得较高电子迁移率，器件中的复合区域通常靠近电子传输层一侧，这就要求电子传输材料需要具有较高三线态能级来限域激子，尤其是高能量的蓝光激子。而高三线态（弱共轭）和高迁移率（强共轭）一直是有机分子设计中难以调和的矛盾，此外更宽的带隙也会导致较差的热稳定性，这些难题始终限制着OLED电子传输材料的发展。本文分类介绍了高性能的电子传输材料所需要具备的几点特性，包括热稳定性、光化学稳定性、电子迁移率、前线轨道能级和三重态能级等，并且综述了21世纪以来OLED小分子电子传输材料的重要研究进展，以期对未来开发理想的电子传输材料提供参考。

研究了分子束外延生长条件对高铟组分InGaAs材料性能的影响，分析了生长温度、V/III比和As分子束形态对In_0.74Ga_0.26As材料光致发光和X射线衍射峰强度、本底载流子浓度和迁移率的影响。测试结果表明：适中的生长温度和V/III比可以提高材料晶格质量，减少非辐射复合，降低本底杂质浓度。As分子束为As₂时In_0.74Ga_0.26As材料质量优于As₄分子束。当生长温度为570 ℃，As分子束形态为As₂，V/III比为18时，可以获得较高的光致发光和X射线衍射峰强度，室温和77 K下的本底载流子浓度分别达到6.3×10¹⁴ cm^-3和4.0×10¹⁴ cm^-3，迁移率分别达到13 400 cm²/Vs和45 160 cm²/Vs。

基于90 nm InP HEMT工艺，设计了一款220 GHz功率放大器太赫兹单片集成电路，该放大器采用片上威尔金森功分器结构实现了两路五级共源放大器的功率合成。在片测试结果表明，200~230 GHz频率范围内，功率放大器小信号增益平均值18 dB。频率为210~230 GHz范围内该MMIC放大器饱和输出功率优于15.8 mW，在223 GHz时最高输出功率达到20.9 mW，放大器芯片尺寸为2.18 mm×2.40 mm。