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The Global ETD Search service is a free service for researchers
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 71 to 80 of 3317 (0.058 seconds)Spelling suggestions: "subject:"semiconductor"" "subject:"emiconductor""
| 71 |
Gate controlled transport in a GaAs:AlGaAs heterojunctionThornton, T. J. January 1987 (has links)
Optical and electron beam lithography has been used to fabricate high mobility GaAs:AlGaAs heterojunction FETs in which the current is controlled by Schottky barrier gates with novel geometries. The two dimensional electron gas (2DEG) at the heterojunction interface had a low temperature mobility of ~250,000 cm<SUP>2V<SUP>-1s<SUP>-1</SUP> and a carrier concentration of 4.3x10<SUP>11cm<SUP>-2</SUP>. Narrow channels of the 2DEG were defined by means of a split gate which consisted of two gold pads 15μm long, separated by ~1μm. A negative voltage applied to the gate removes carriers from beneath the gate resulting in a narrow channel in the gap. The channel width can be reduced to zero by further decreasing the gate voltage. At low temperatures (T ≤ 4.2K) the electron phase coherence length, Lφ, is greater than the width, W, and the transport is quasi one dimensional. Analysis of the low temperature magnetoconductance showed that for a channel of width ~450AA the phase coherence length varied as Lφsim 0.16μ m(T/K)^-0.35±0.06. A similar result was obtained from an analysis of the universal conductance fluctuations in channels of width ~ 1800AA. This suggests that the dominant electron scattering mechanism was due to electromagnetic fluctuations in the 2DEG for which Lφ would be expected to vary as T^-1/3. For high magnetic fields (O < B ≤ 8T) the magnetoconductance showed oscillations which were explained in terms of the magnetic depopulation of one dimensional subbands. A number of fine gate FETs were made with gate lengths of ~ 1000AA. The I-V characteristics of a strongly depleted channel were measured at 4.2K and it was found that I ∝V<SUP>3/2</SUP> so that the current flow was dominated by space charge effects. For larger source drain biases I ∝ V and this was explained as being due to velocity saturation. The second voltage differential δ2V/δI<SUP>2</SUP> showed structure at ~ 40meV and ~ 80meV and this was attributed to optic phonon emission by hot electrons.
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| 72 |
The study of defects in bismuth germanium oxide (Biâ†1â†2GeOâ†2â†0) using phonon echoes and other techniquesTerry, Ian January 1988 (has links)
No description available.
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| 73 |
Studies of some metal phthalocyanines for gas sensor applicationsMohammed, K. A. January 1987 (has links)
No description available.
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| 74 |
GaAs diodes in the relaxation regime used for radiation detectionSantana-Corte, Juan Martin January 1997 (has links)
No description available.
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| 75 |
Irradiated silicon detectors as relaxation devicesMcPherson, Michael January 1997 (has links)
No description available.
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| 76 |
Steady state and transient photoconductivity in n-type amorphous siliconMerazga, Amar January 1990 (has links)
No description available.
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| 77 |
A study of epitaxial growth of CaFâ†2 on siliconHoward, L. K. January 1989 (has links)
No description available.
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| 78 |
An investigation of the microstructure of AuGeNi contacts to InPGraham, R. J. January 1984 (has links)
No description available.
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| 79 |
The design, manufacture and testing of a low-cost cleanroom robot for handling silicon wafersLopez Parra, Marcelo January 1994 (has links)
No description available.
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| 80 |
Coherent optical transient effects in semiconductor quantum wellsDenton, Graham John January 1994 (has links)
No description available.
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