Author Affiliations
Abstract
1 Laboratory of Solid State Optoelectronics Information Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
2 College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 101804, China
3 School of Physics Science and Technology, Xinjiang University, Urumqi 830046, China
4 School of New Energy and Electronics, Yancheng Teachers University, Yancheng 224002, China
5 Key Laboratory of Optoelectronic Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Ex situ characterization techniques in molecular beam epitaxy (MBE) have inherent limitations, such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber. In recent years, the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques. These techniques, such as reflection high-energy electron diffraction, scanning tunneling microscopy, and X-ray photoelectron spectroscopy, allow direct observation of film growth processes in real time without exposing the sample to air, hence offering insights into the growth mechanisms of epitaxial films with controlled properties. By combining multiple in situ characterization techniques with MBE, researchers can better understand film growth processes, realizing novel materials with customized properties and extensive applications. This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research. In addition, through further analysis of these techniques regarding their challenges and potential solutions, particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information, we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.
epitaxial growth thin film in situ characterization molecular beam epitaxy (MBE) Journal of Semiconductors
2024, 45(3): 031301
1 南京信息工程大学 电子与信息工程学院, 江苏 南京 210044
2 南京大学 电子科学与工程学院, 江苏 南京 210093
利用金属有机化合物化学气相沉积(MOCVD)技术,在不同晶面的蓝宝石(Al2O3)衬底上实现了极性(0002)面、半极性(11-22)面和非极性(11-20)面InN薄膜的外延生长,并通过多种表征手段对三个不同极性面InN薄膜的结构和光学特性进行了系统研究。X射线衍射(XRD)曲线展示了(0002)、(11-22)和(11-20)面InN较强的衍射峰,表明InN薄膜具有较高的成膜质量。通过扫描电子显微镜(SEM)表面图发现,极性(0002)面InN的表面形貌较光滑,而半极性和非极性InN表面均存在未完全合并的孔洞。光致发光(PL)光谱展示,不同极性面InN的峰值能量在0.63 eV附近,并从极性、半极性到非极性逐渐红移。此外,可见-红外分光光度计测得的透射谱显示,极性(0002)面InN的吸收边约为0.85 eV,而半极性(11-22)面和非极性(11-20)面InN的吸收边约为0.78 eV,表明极性InN具有更大的斯托克斯位移。
半极性面 非极性面 InN薄膜 外延生长 semipolar nonpolar InN film epitaxial growth
1 西安电子科技大学, 西安 710071
2 中国科学院 微电子研究所, 北京 100029
3 天津市滨海新区微电子研究院, 天津 300459
提出了一种适用于低电压工作的毫米波AlN/GaN MIS-HEMT器件, 开展了材料外延结构的设计, 在SiC衬底上生长了AlN/GaN外延材料。基于此材料开展了器件制作, 优化了高温快速退火工艺, 获得良好的欧姆接触电阻。对所制备的器件进行直流测试, 结果显示, 电流输出能力为2.4 A/mm, 跨导极值为518 mS/mm, 小信号ft达到85 GHz, fmax大于141 GHz。在5G毫米波段28 GHz频率点测试了大信号特性, 当VDS =3 V时, 输出功率密度为0.55 W/mm, 功率附加效率(PAE)为40.1%; 当VDS = 6 V时, 输出功率密度为1.6 W/mm, PAE达到47.8%。该器件具有低压毫米波应用的潜力。
氮化铝/氮化硅 外延材料 低工作电压 毫米波 氮化铝势垒 AlN/SixN epitaxial material low operating voltage millimeter wave MIS-HEMT MIS-HEMT AlN barrier
Author Affiliations
Abstract
1 National Engineering Research Center for Optoelectronic Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
2 College of Materials Science and Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
Output power and reliability are the most important characteristic parameters of semiconductor lasers. However, catastrophic optical damage (COD), which usually occurs on the cavity surface, will seriously damage the further improvement of the output power and affect the reliability. To improve the anti-optical disaster ability of the cavity surface, a non-absorption window (NAW) is adopted for the 915 nm InGaAsP/GaAsP single-quantum well semiconductor laser using quantum well mixing (QWI) induced by impurity-free vacancy. Both the principle and the process of point defect diffusion are described in detail in this paper. We also studied the effects of annealing temperature, annealing time, and the thickness of SiO2 film on the quantum well mixing in a semiconductor laser with a primary epitaxial structure, which is distinct from the previous structures. We found that when compared with the complete epitaxial structure, the blue shift of the semiconductor laser with the primary epitaxial structure is larger under the same conditions. To obtain the appropriate blue shift window, the primary epitaxial structure can use a lower annealing temperature and shorter annealing time. In addition, the process is less expensive. We also provide references for upcoming device fabrication.
catastrophic optical damage primary epitaxial structure impurity-free vacancy disordering quantum well intermixing non-absorption window Journal of Semiconductors
2023, 44(10): 102302
红外与激光工程
2023, 52(5): 20220731
1 西安电子科技大学宽带隙半导体技术国家重点学科实验室, 西安 710071
2 西安电子科技大学石墨烯陕西联合重点实验室, 西安 710071
3 西电芜湖研究院, 芜湖 241000
4 南京电子器件研究所碳基电子学CETC重点实验室, 南京 210016
随着氮化镓(GaN)在高功率领域的广泛应用, GaN基器件的散热性能成为了制约其功率密度的主要因素, 因此开辟新的热管理方案至关重要。具有高热导率的金刚石衬底可以用于改善GaN器件的散热问题。然而, 由于金刚石和GaN之间的天然晶格失配, 在金刚石衬底上GaN的直接外延仍然是一个难以克服的问题。本工作以二维材料/Al组分渐变的AlGaN异质结作为衬底与外延层之间的成核层, 在多晶金刚石衬底上实现了单晶GaN薄膜的范德瓦耳斯外延。其中, 二维材料可以有效屏蔽掉衬底与外延层晶格不匹配带来的不良影响, 而Al组分渐变的AlGaN缓冲层结构可实现Ga原子和N原子的有序迁移, 进而精确地控制GaN薄膜的生长。本工作为异质衬底上高质量生长氮化物提供新思路。实验结果表明, 成核层的引入有效地消除晶格失配的影响, 从而打破了金刚石衬底上难以直接外延单晶GaN薄膜的瓶颈。本工作为GaN基器件的功率密度的进一步提升提供了基础。
金刚石 范德瓦耳斯外延生长 高散热 Al组分渐变 二维材料 GaN GaN diamond van der Waals epitaxial growth high heat dissipation Al component gradient two-dimensional material
本文利用等离子体辅助分子束外延(PA-MBE)系统, 对常规连续外延生长和金属调制外延(MME)生长AlN薄膜进行研究。研究发现: 常规连续外延方法生长模式不易控制, 容易出现过度富Al和富N模式生长, 而且微富Al模式生长还会出现一些凹坑, 表面形貌较粗糙; 然而利用MME方法生长AlN薄膜, 通过精准调控Al源和N源快门打开、关闭时间, 可以获得形貌较好的AlN薄膜。通过调整优化获得的MME方案为: 首先Al源快门打开30 s, 然后Al源和N源快门打开60 s, 最后单独打开N源快门72 s; 单一周期内, Al源快门打开时间与N源快门打开时间比例为0.7。以上述方案为一个周期进行循环生长40个周期, 可获得粗糙度低至0.3 nm(2 μm×2 μm), 几乎无凹坑的AlN薄膜。
金属调制 分子束外延 外延生长 氮化铝 粗糙度 metal modulation molecular beam epitaxy epitaxial growth aluminum nitride roughness
1 中国科学院半导体研究所, 半导体材料科学重点实验室, 北京 100083
2 中国科学院大学, 材料与光电研究中心, 北京 100049
二维超宽禁带半导体材料六方氮化硼(h-BN)具有绝缘性好、击穿场强高、热导率高, 以及良好的稳定性等特点, 且其原子级平整表面极少有悬挂键和电荷陷阱的存在, 使其有潜力成为二维电子器件的衬底和栅介质材料。实现h-BN应用的关键在于生长高质量的h-BN单晶薄膜, 本文详细介绍了在过渡金属衬底、绝缘介质衬底和半导体材料表面外延生长h-BN的方法及其研究进展。在具有催化活性的过渡金属衬底(铜、镍、铁、铂等)上可以外延得到高质量的二维h-BN, 而在绝缘介质或半导体材料衬底上直接生长h-BN单晶薄膜更具挑战性。蓝宝石以其良好的热稳定性和化学稳定性成为外延h-BN的首选衬底, 蓝宝石衬底上生长h-BN薄膜的方法主要有化学气相沉积、分子束外延、离子束溅射沉积、金属有机气相外延, 以及高温后退火等, 通过这些方法可以在蓝宝石衬底上外延得到h-BN单晶薄膜, 还可以集成到现有的一些III-V族化合物半导体的外延生长工艺之中, 为h-BN的大面积应用奠定基础。此外, 石墨烯、硅和锗等半导体材料衬底上生长h-BN单晶薄膜也是当前研究的一个热点, 这为基于h-BN的异质结制备及其应用提供了新的方向。
六方氮化硼 外延生长 薄膜 二维材料 宽禁带半导体 hexagonal boron nitride epitaxial growth thin film two-dimensional material wide band gap semiconductor