Intraband Processes and New Device Concepts in SemiconductorHomo and Hetero Junctions

9412248 Perera将对新的半导体器件概念和带内工艺进行研究，主要是在高性能红外成像和发射器系统中的潜在应用，其中将对最近出现的分子束外延生长技术提供的独特维度和成分控制能力进行修订，以演变出特殊类型的新型结和多量子阱(MQW)格式。在先前的NSF程序下开发的一种这样的格式中，通过对注入的或分子束外延生长的光电发射区的重掺杂，将p-i-n同质结中的界面功函数控制在低值(对应于VLWIR到FIR范围内的光能)。采用分析和实验方法来了解临界掺杂和尺寸参数以及偏置条件对探测器和阵列性能的影响，从而提出在更高的低温温度下具有更高性能的分子束外延生长的多结结构。这项工作的主要意义在于为大面积、均匀、具有多种特殊能力的探测器阵列的发展奠定了技术基础，从而大大提高了NE-T响应度。VLWIR MQW(Al，Ga，As)探测器的最新成功将通过将光导和光伏(微带)结构的截止波长扩展到16微米以上，并检查瞬时操作模式作为提高响应和探测器的手段来开发。还将与康奈尔大学、国家研究中心、加州大学洛杉矶分校和喷气推进实验室的分子束外延专家合作，研究提高(Al，Ga)As势垒生长质量的可行性，作为降低较长波长暗电流的一种手段。就像硅同质结的情况一样，固有的一致性和低功率要求，应该使它们在更长波长上的性能优于HgCdTe探测器阵列。MQW红外发射体结构的令人鼓舞的结果将为进一步的模拟工作和结合三能级和三势垒特征的实验装置提供良好的基础，以此作为提高布居反转效率的手段。还将研究其他材料系统(如InGaAs/InAlAs)在MWIR范围内的高红外发射潜力。MQW发射器技术将产生波长从MWIR到FIR的稳定、可集成的大面积红外源，用于目前由小面积化学不稳定的HgCdTe和PbSnTe激光二极管处理的应用。***

9412248 Perera Research on novel semiconductor device concepts and intraband processes leading to potential applications primarily in high-performance infrared imaging and emitter systems will be performed in which the unique dimensional and compositional control capability offered by recently emerging MBE growth technology will be revised to evolve special types of novel junction and multi-quantum well (MQW) formats. In one such format, developed under a previous NSF program, the interfacial work function in p-i-n homojunctions is controlled at low values (corresponding to optical energies in the VLWIR to FIR range) by heavy doping of the implanted or MBE-grown photo-emitter region. Analytical and experimental approaches aimed at understanding the influence of critical doping and dimensional parameters, and of bias conditions, on detector and array performance be employed to suggest MBE-grown multi-junction structures with the potential for higher performance at more elevated cryogenic temperatures. The main significance of this work is in establishing a technology base for the evolution of large area, uniform detector arrays with a multi-special capability for greatly improved NE T responsivity. Recent successes with VLWIR MQW (A1, Ga, As) detectors will be exploited by extending the cutoff for both photoconductive and photovoltaic (miniband) structures to wavelengths beyond 16 um, and examining transient operation modes as a means of improving response and detectivity. Working in conjunction with MBE experts at Cornell, NRC, UCLA and JPL the feasibility of improved quality of (A1,Ga)As barrier growth, as a means of lowering dark current at longer wavelengths will also be studied. As is the case for Si homojunctions, the inherent uniformity, and their low power requirements, should enable them to out perform HgCdTe detector arrays at longer wavelengths. Encouraging results for MQW IR emitter structures will provide an excellent basis for further modeling efforts and experimental d evices incorporating three-level and triple-barrier features as a means to improve efficiency of population inversion. Other material systems (e.g. InGaAs/InA1As) will also be examined for the potential of high IR emission in the MWIR range. The MQW emitter technology should lead to stable, integratable, large area IR sources at wavelengths extending from MWIR to FIR, for applications currently being addressed by small-area chemically unstable HgCdTe and PbSnTe laser diodes. ***