Interface Dipolar Engineering in III-V Semiconductors

III-V 族半导体中的界面偶极子工程

• 批准号: 9819659
• 负责人: Marshall Nathan
• 金额: $ 64万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-15 至 2003-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9819659&HistoricalAwards=false
• 关键词: Interface; Dipolar; Engineering; III; Semiconductors

This FRG (Focused Research Group) project aims for greater understanding of materials science and device physics aspects of dipole layers at heterojunction interfaces, and to modify them for improved device performance across a variety of common compound semiconductor structures: lasers, HBTs, MOSFETs, HEMTs, and Schottky barriers. The project involves theory, growth, characterization, and prototype device studies. First principle calculations will be performed by collaborators at EPFL (Switzerland), and coupled with material processing for improved device performance. Recently dual purpose molecular beam epitaxy (MBE) facilities devoted to the exploration of interface properties and the fabrication of working devices have produced tunability of band offsets and Schottky barriers through local modifications of the atomic termination of critical interfaces. In parallel with experiment, a convergence of different theoretical models, including first principles calculations, the theoretical alchemy approach and linear response theory results, are establishing a common theoretical framework. Most theoretical and experimental studies have identified heterovalent semiconductor junctions with polar orientation as those that exhibit the strongest dependence of interface properties on local interface termination. Therefore IV/III-V, II-VI/III-V, III-V/IV/III-V and III--V/II-VI/III-V interfaces may represent a class of highly tunable interface systems, as compared to the more conventional isovalent systems (e.g., III-V/III-V) where the valence difference across each interface allows fabrication of large electrostatic dipoles with orientation and magnitude largely controlled by the growth conditions.For heterojunction interfaces, parameters such as the valence and conduction band discontinuities, and the built-in potentials affect carrier confinement on both sides of the active region where radiative recombination occurs in heterojunction lasers, emitter efficiencies in HBT's, as well as the gate voltage swing and the gate leakage current in MOSFET and HEMT structures. For metal/semiconductor interfaces, present in all solid state devices, the possibility of reducing or increasing the Schottky barrier height without changing the doping of the semiconductor constituent would enhance ability to fabricate low resistivity contacts to new wide bandgap materials for which doping technology is still limited (e.g., III-V nitrides, silicon carbide, diamond), simplify the exploitation of ballistic transport in practical devices, decrease the leakage current in MESFET's, and potentially yield Schottky barrier photon detectors with tunable long -wavelength cut-off and/or lower dark currents. Thus, the project seeks to exploit heterovalency-induced, extrinsic local interface dipoles in a variety of III-V materials systems of current practical interest, including AlGaAs/GaAs, GaInAs/InP, GaInP/GaAs, and AlGaN/GaN. Different ultrathin heterovalent interlayers (e.g., Si, Ge, Si-C, Zn-O) will be fabricated by MBE to tune the band alignments as well as in related metal/semiconductor junctions. Interlayer type and growth conditions which minimize out-diffusion, and assess the range of offset tuning that can be achieved in high-quality, device grade structures will be determined. The ultimate goal is to clarify the microscopic mechanisms that determine the offset tuning while developing a series of new interfacial engineering principles for device optimization. This FRG project is co-supported by two NSF programs, and the MPS OMA(Office of Multidisciplinary Activities).%%%The project addresses basic research issues in a topical area of materials science and engineering having high potential technological relevance. The research will contribute new knowledge at a fundamental level to important fabrication aspects of electronic/photonic devices. The basic knowledge and understanding gained from the research is expected to contribute to improving the perform-ance and stability of advanced devices and circuits. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area.***

该FRG（重点研究小组）项目旨在更好地了解异质结界面偶极子层的材料科学和器件物理方面，并对其进行修改，以提高各种常见化合物半导体结构（激光器、HBTs、mosfet、hemt和肖特基势垒）的器件性能。该项目涉及理论、发展、特性和原型装置研究。第一性原理计算将由EPFL（瑞士）的合作者进行，并结合材料处理以提高设备性能。最近，双用途分子束外延（MBE）设备致力于探索界面性质和工作器件的制造，通过局部修改关键界面的原子终端，产生了能带偏移和肖特基势垒的可调性。在实验的同时，不同理论模型的融合，包括第一性原理计算、理论炼金术方法和线性响应理论结果，正在建立一个共同的理论框架。大多数理论和实验研究已经确定了具有极性取向的异价半导体结，这些结表现出对局部界面终止的最强依赖性。因此，IV/III-V, II-VI/III-V， III-V/IV/III-V和III—V/II-VI/III-V界面可能代表一类高度可调的界面系统，与更传统的等价系统（例如III-V/III-V）相比，每个界面的价差允许制造大型静电偶极子，其取向和大小主要由生长条件控制。对于异质结界面，诸如价带不连续、导带不连续和内置电位等参数影响异质结激光器中发生辐射复合的有源区域两侧的载流子约束、HBT中的发射极效率，以及MOSFET和HEMT结构中的栅极电压摆幅和栅极漏电流。对于存在于所有固态器件中的金属/半导体界面，在不改变半导体成分掺杂的情况下降低或增加肖特基势垒高度的可能性，将增强与掺杂技术仍然有限的新型宽带隙材料（例如III-V型氮化物、碳化硅、金刚石）制造低电阻率触点的能力，简化实际器件中弹道输运的开发。减少MESFET的泄漏电流，并有可能产生具有可调谐长波长截止和/或更低暗电流的肖特基势垒光子探测器。因此，该项目寻求在当前实际兴趣的各种III-V材料系统中利用杂价诱导的外源性局部界面偶极子，包括AlGaAs/GaAs， GaInAs/InP， GaInP/GaAs和AlGaN/GaN。不同的超薄异价间层（例如，Si, Ge, Si- c, Zn-O）将由MBE制造，以调整能带对准以及相关的金属/半导体结。将确定层间类型和生长条件，以最大限度地减少向外扩散，并评估可在高质量器件级结构中实现的偏移调谐范围。最终目标是阐明确定偏置调谐的微观机制，同时为器件优化开发一系列新的界面工程原理。该FRG项目由两个NSF项目和MPS OMA（多学科活动办公室）共同支持。该项目涉及材料科学与工程领域的基础研究问题，具有很高的潜在技术相关性。该研究将在基础层面为电子/光子器件的重要制造方面提供新的知识。从研究中获得的基本知识和理解有望有助于提高先进器件和电路的性能和稳定性。该计划的一个重要特点是通过在基础和技术重要领域培养学生，将研究和教育相结合