tudy of the Surface Cleaning Effects to the InGaAs Quantum Well Wires by Atomic Force Microscopy and Photoluminescence Spectroscopy

1992 ◽  
Vol 259 ◽  
Author(s):  
I-Hsing Tan ◽  
Song Shi Stone ◽  
Craig Prater ◽  
Richard Mirin ◽  
Evelyn Hu ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Optical Property ◽  
Quantum Well ◽  
Surface Cleaning ◽  
Force Microscopy ◽  
Luminescence Efficiency ◽  
Atomic Force ◽  
Surface Oxides ◽  
Quantum Well Wires ◽  
Ingaas Quantum Well

ABSTRACTThe efficacy of residual photoresist removal on the top surface of the InGaAs QWW grating and the effects of surface oxides on the optical property of quantum well wires (QWWs) were examined through atomic force microscopy (AFM) and photoluminescence (PL) spectroscopy. Different resist removal treatments, including acetone, ozone and diluted HC1 were evaluated. Both AFM and PL measurements reveal that with the surface cleaning processing we have developed, high luminescence efficiency from the QWWs is conserved after removal of the residual photoresist.

Si/SiGe Nanostructures Fabricated by Atomic Force Microscopy Oxidation

2001 ◽  
Vol 686 ◽  
Author(s):  
Xiang-Zheng Bo ◽  
Leonid P. Rokhinson ◽  
Haizhou Yin ◽  
D. C. Tsui ◽  
J. C. Sturm
Keyword(s):  
Atomic Force Microscopy ◽  
High Resolution ◽  
Quantum Well ◽  
Bias Voltage ◽  
Silicon Germanium ◽  
Force Microscopy ◽  
Atomic Force ◽  
Line Widths ◽  
Humidity Environment ◽  
Strained Sige

AbstractIn this work, local AFM oxidation technique in a controlled humidity environment has been used to create small features in strained SiGe alloys. When directly oxidizing SiGe alloys, minimum line widths of 20nm were achieved by adjusting parameters such as the bias voltage on the microscope tip and the tip writing speed. It was found that when bias voltage increases, and/or when the tip writing speed decreases, the oxidation height of silicon-germanium increases. In contrast to conventional thermal oxidation, the oxide height on SiGe alloys is slightly less than that on Si. Finally, this method was used to successfully cut conducting SiGe quantum well lines with high resolution.

scholarly journals Nonuniform Morphology and Luminescence Properties of a Molecular Beam Epitaxy GaN Film from Atomic Force Microscopy, Scanning Electron Microscopy and Cathodoluminescence

1997 ◽  
Vol 2 ◽  
Author(s):  
L.-L. Chao ◽  
G. S. Cargill ◽  
C. Kothandaraman ◽  
D. Cyr ◽  
G. Flynn ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Room Temperature ◽  
Force Microscopy ◽  
Luminescence Efficiency ◽  
Atomic Force ◽  
Background Material ◽  
Gan Film ◽  
Scanning Electron

Complex faceted features of micrometer sizes and with intense luminescence rise 200-300 nm above the surface of a GaN thin film grown by molecular beam epitaxy on (0001) sapphire. Cathodoluminescence measurements at room temperature and at 8K were used to investigate the luminescence properties of these microfeatures in comparison with those of the background GaN material. The morphology of the micro-features was studied by scanning electron microscopy and by atomic force microscopy.GaN and related compounds have been considered as promising materials for light emitting devices in the short wavelength visible and UV spectral regions because of their direct, wide band gaps and high luminescence efficiency. Remarkable, rapid success has been achieved in developing devices based on III-V nitrides, which allows these material systems to rival other systems under development [1]. Blue-green LEDs fabricated from InGaN/AlGaN double-heterostructure layers on sapphire substrates by Nichia Chemical Industries in Japan are commercially available, despite the presence of high extended defect densities in the 1010 /cm2 range [2]. In December 1995, an important milestone in the development of nitride lasers was reached; Nakamura et al. in Nichia demonstrated the first nitride-based laser diode which operated at 417 nm under pulsed conditions at room temperature [3].The morphology and spatial distribution of luminescence in GaN thin films have been investigated by several research groups [4], [5], [6], although most efforts have been directed to developing appropriate growth conditions for improved film quality. From observations by scanning electron microscopy (SEM) and atomic force microscopy (AFM), Trager-Cowan et al. described an MBE-grown GaN film which contained an assembly of oriented hexagonal crystallites rising above a background of polycrystalline or amorphous material [4]. All the crystallites, oriented in a similar fashion, had roughly the same sizes, 1 or 2 μm across a hexagonal face and about 1 μm high. These crystallites were much brighter than the surrounding background material in panchromatic low-temperature cathodoluminescence (CL) images. Trager-Cowan et al. concluded that the crystallites were of better quality than the background material. They also observed a green emission band, attributed to impurities, which became weaker for higher electron beam voltages, generating luminescence from deeper in the film. From this observation, they concluded that higher quality material is located closer to the film's outer surface. Spatial variation of the luminescence efficiency from MOCVD-grown films has also been observed by Ponce et al[5]. in their room-temperature CL microscopy studies. Their results showed significant nonuniformities in both the band-edge and yellow band emissions. Although they reported no faceted island structures, one of their samples had “marked surface features” and consisted of hexagonal crystals 10 to 50 μm in diameter. The crystals gave strong band-to-band (364 nm) luminescence.In this paper, the morphology of a GaN film grown on (0001) sapphire by MBE is characterized by SEM and AFM, and CL measurements are used to investigate the luminescence properties of the film at room temperature and at 8K. Some regions of this film are similar to the one described by Trager-Cowan et al. [4] in having micron sized, brightly luminescent islands. The hexagonal facet angles and bright luminescence of islands in our film also resemble the larger scale, more regularly shaped hexagonal crystals of Ponce et al. [5]. These regions lie on the boundary of excess gallium growth conditions. Our results differ from those of Trager-Cowan in terms of the island morphologies and the spectral character of luminescence from the islands and from the background material. Possible causes of the large variations in luminescence efficiency are discussed.

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