Open Access. Powered by Scholars. Published by Universities.®
- Institution
Articles 1 - 6 of 6
Full-Text Articles in Engineering
Anomalous Stranski-Krastanov Growth Of (111)-Oriented Quantum Dots With Tunable Wetting Layer Thickness, Christopher F. Schuck, Simon K. Roy, Trent Garrett, Paul J. Simmonds
Anomalous Stranski-Krastanov Growth Of (111)-Oriented Quantum Dots With Tunable Wetting Layer Thickness, Christopher F. Schuck, Simon K. Roy, Trent Garrett, Paul J. Simmonds
Materials Science and Engineering Faculty Publications and Presentations
Driven by tensile strain, GaAs quantum dots (QDs) self-assemble on In0.52Al0.48As(111)A surfaces lattice-matched to InP substrates. In this study, we show that the tensile-strained self-assembly process for these GaAs(111)A QDs unexpectedly deviates from the well-known Stranski-Krastanov (SK) growth mode. Traditionally, QDs formed via the SK growth mode form on top of a flat wetting layer (WL) whose thickness is fixed. The inability to tune WL thickness has inhibited researchers’ attempts to fully control QD-WL interactions in these hybrid 0D-2D quantum systems. In contrast, using microscopy, spectroscopy, and computational modeling, we demonstrate that for GaAs(111)A QDs, we …
Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara
Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara
Physics and Astronomy Faculty Publications
The present study examines the interaction of hydrogen and nitrogen plasmas with gallium in an effort to gain insights into the mechanisms behind the synergetic effect of plasma and a catalytic metal. Absorption/desorption experiments were performed, accompanied by theoretical-computational calculations. Experiments were carried out in a plasma-enhanced, Ga-packed, batch reactor and entailed monitoring the change in pressure at different temperatures. The results indicated a rapid adsorption/dissolution of the gas into the molten metal when gallium was exposed to plasma, even at a low temperature of 100 °C. The experimental observations, when hydrogen was used, indicate that gallium acts as a …
Quantum Dot Band Gap Investigations, John Ryan Peterson
Quantum Dot Band Gap Investigations, John Ryan Peterson
Student Works
Improving solar panel efficiency has become increasingly important as the world searches for cheap renewable energy. Recent developments in the industry have focused on multi-layer cells, some of which use semiconducting dyes to absorb light in place of crystalline solids. In this paper, I characterize various dyes recently synthesized for use in solar panels. These dyes contain semiconducting nanoparticles enclosed primarily by the protein ferritin to limit particle size. The band gaps were measured using either optical absorption spectroscopy or measuring the photoluminescence spectrum, depending on the type of semiconductor. The results indicate that both manganese oxide and lead sulfide …
Complementary Metal-Oxide Semiconductor-Compatible Detector Materials With Enhanced 1550 Nm Responsivity Via Sn-Doping Of Ge/Si(100), Richard T. Beeler, Jay Mathews, Mee-Yi Ryu, Yung-Kee Yeo, Jose Menendez, John Kouvetakis
Complementary Metal-Oxide Semiconductor-Compatible Detector Materials With Enhanced 1550 Nm Responsivity Via Sn-Doping Of Ge/Si(100), Richard T. Beeler, Jay Mathews, Mee-Yi Ryu, Yung-Kee Yeo, Jose Menendez, John Kouvetakis
Faculty Publications
Previously developed methods used to grow Ge1−ySny alloys on Si are extended to Sn concentrations in the 1019−1020 cm−3 range. These concentrations are shown to be sufficient to engineer large increases in the responsivity of detectors operating at 1550 nm. The dopant levels of Sn are incorporated at temperatures in the 370–390 °C range, yielding atomically smooth layers devoid of threading defects at high growth rates of 15–30 nm/min. These conditions are far more compatible with complementary metal-oxide semiconductor processing than the high growth and processing temperatures required to achieve the same …
Supralinear Photoconductivity Of Copper Doped Semi-Insulating Gallium Arsenide, K. H. Schoenbach, R. P. Joshi, F. Peterkin, R. L. Druce
Supralinear Photoconductivity Of Copper Doped Semi-Insulating Gallium Arsenide, K. H. Schoenbach, R. P. Joshi, F. Peterkin, R. L. Druce
Bioelectrics Publications
We report on the intensity dependent supralinear photoconductivity in GaAs:Si:Cu material. The results of our measurements show that the effective carrier lifetime can change over two orders of magnitude with variations in the intensity of the optical excitation. A threshold intensity level has been observed and can be related to the occupancy of the deep copper level. Numerical simulations have also been carried out to analyze the trapping dynamics. The intensity dependent lifetimes obtained from the simulations match the experimental data very well. Finally, based on the nonlinear intensity dependence of the effective lifetimes, a possible low‐energy phototransistor application for …
Temporal Development Of Electric Field Structures In Photoconductive Gaas Switches, K. H. Schoenbach, J. S. Kenney, F.E. Peterkin, R. J. Allen
Temporal Development Of Electric Field Structures In Photoconductive Gaas Switches, K. H. Schoenbach, J. S. Kenney, F.E. Peterkin, R. J. Allen
Bioelectrics Publications
The temporal development of the electric field distribution in semi‐insulating GaAs photoconductive switches operated in the linear and lock‐on mode has been studied. The field structure was obtained by recording a change in the absorption pattern of the switch due to the Franz–Keldysh effect at a wavelength near the band edge of GaAs. In the linear mode, a high field layer develops at the cathode contact after laser activation. With increasing applied voltage, domainlike structures become visible in the anode region and the switch transits into the lock‐on state, a permanent filamentary electrical discharge. Calibration measurements show the field intensity …