Determination of Nitride Semiconductor Parameters Using Light-Induced Transient Gratings

我们提出了对GaN基三元和四元材料和器件中光生电子和空穴的实验和理论研究，包括在UV范围内具有带隙的化合物。我们将使用光诱导瞬变光栅(LITG)系统，它利用了准稳态和时间分辨光致发光光谱等无损技术，在不同波长的激光激励下，在8K到600K的温度范围内。我们的研究将包括不同温度下的发光、激发强度和波长的研究、时间分辨发光的研究、受激发射的研究以及LITG测量。这将使我们能够确定在可见光范围内的载流子密度、寿命、扩散系数和表面复合速率(将大面积晶片映射到紫外光中)。将基于LITG的新技术获得的结果与传统发光光谱的结果进行比较，将使我们对这些问题有一个新的认识，这些问题对于宽带隙氮化物在发光和探测器件中的开发至关重要。氮化物基宽禁带半导体的物理在许多关键领域与更传统的半导体，如硅或砷化镓有很大的不同。这与一种不同的(更复杂的)对称性有关，它允许自发极化。确定氮化物的基本半导体参数并在适当情况下将它们与材料的生长和制造过程相关联，对于发展新的宽带半导体科学以及支持从固态照明到超高功率雷达、从水净化到生物危害检测等应用的工业至关重要。

We propose experimental and theoretical investigations of light generatedelectrons and holes in GaN-based ternary and quaternary materials anddevices, including compounds with band gap in UV range. We will use Light-Induced Transient Gratings (LITG) system, which exploitsnondestructive techniques including the quasi-steady-state and time-resolvedphotoluminescence spectroscopy in the temperature range from 8 K to 600 Kunder laser excitation at different wavelengths. Our studies will include studies of luminescence at different temperatures,excitation intensities and wavelengths, time-resolved luminescence,investigations of stimulated emission, and LITG measurements. This willallow us to determine carrier densities, lifetimes, diffusion coefficients,and surface recombination rates (mapping large area wafers) throughout thevisible range into UV.Comparison of results obtained by the new technique based on LITG with theresults of the conventional luminescence spectroscopy will provide a newinsight into the problems, which are of the primary importance forexploitation of the wide-band-gap nitrides in light emitting and detectingdevices.Physics of nitride-based wide band gap semiconductors is dramaticallydifferent in many key areas from that of more conventional semiconductors,such as silicon or GaAs. This is linked to a different (and more complex)symmetry that allows for spontaneous polarization. Determining basicsemiconductor parameters for nitrides and relating them to the materialsgrowth and fabrication process, where appropriate, is crucial for developingnew wide band semiconductor science and for supporting industry withapplications ranging from solid state lighting to ultra high power radars,from water purification to biological hazard detection.