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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the 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.
31

Growth of Lattice-matched Ternary and Quaternary Compound Semiconductors on InP by Molecular Beam Epitaxy

Lai, Min-Feng 09 July 2002 (has links)
This work is to control the fluxes of the Ga, In and Al sources in our MBE system to grow lattice-matched InGaAs, InAlAs and InGaAlAs epi-layers on InP substrates. With the As overpressure condition in the MBE system, we can control the temperature of Ga K-cell to modulate the flux of Ga. In ideal situation, the flux of Ga has a direct ratio with the GaAs growth rate on GaAs substrate, so we can find the Ga flux dependence on temperature by measuring the RHEED oscillation frequency. From the growth rate data of InGaAs on GaAs substrate at lower In composition, the In flux was obtained by comparing the growth rate ratio to the GaAs case. In the same way, we can also get the flux of Al by the growth of AlAs or AlGaAs on GaAs substrate. With the results of flux experiment, we can modulate the temperature of Ga, In and Al K-cells to compose InGaAs, InAlAs and InGaAlAs lattice-matched on InP substrates. The epi-layer quality was examined by X-ray diffraction and photo-absorption spectrum. We have built the flux equations for the Ga, In and Al sources from the experiment data. With the In K-cell temperature at 833~836¢J, Ga(1) at 931¢J and Al at 1094¢J, we have grown ternary compound semiconductors of In0.532Ga0.468As and In0.523Al0.477As lattice-matched on InP substrates. When the In K-cell temperature at 833~836¢J, Ga(2) at 912¢J and Al at 1059¢J, a quaternary compound semiconductor of In0.527Ga0.245Al0.228As (Eg=1eV) lattice-matched on InP substrate was demonstrated.
32

InGaAlAs/InP Semiconductor Optical Amplifier Structures Grown by Molecular Beam Epitaxy

Tsai, Yao-Tsong 26 June 2003 (has links)
The work of this thesis includes the growth of TE polarization and polarization insensitive semiconductor optical amplifier structures by molecular beam epitaxy. The former is suited to fabricate the SOA and laser of the emitter, the latter is suited to fabricate the SOA of the repeater and receiver. The materials of InAl(1)As, InGa(1)Al(2)As and InGa(2)As were used to be the cladding layer, SCH layer and quantum well(QW), respectively. The first kind of our SOA structures is for 1.55-£gm TE polarization. The materials of InGa(1)As and InGa(2)As were used to be QW and sub-well, respectively. The second kind of our SOA structures is for 1.55-£gm polarization insensitive. To get polarization insensitive characteristics we use tensile strained InGa(3)As material and add two very thin compressive strain layers, InGa(1)As, in QWs to be sub-wells to mostly confine hh1 state. It has the effect of reducing red shift on the e1-hh1 transition and help to partially balance the strain in QW before the thickness of the tensile strained InGa(3)As exceeds one half of the critical layer thickness. These two kinds of structures include three QWs with modulation doping. It can reduce transparency current and noise figure and increase the saturation output power of SOA with the n-type modulation doping. We had successfully grown the polarization insensitive SOA structure for 1.52-£gm. The wavelength of TE polarization SOA structures we grew were at 1.45(µm) and 1.47(µm) and there were somewhat differences between the designed and grown. We can increase the PL efficiency after rapid thermal annealing at 550¢J for 30(s)~45(s).
33

InGaAlAs/InP Electro-Absorption Modulator Structures Grown by Molecular Beam Epitaxy

Lu, Sho-Shou 30 June 2003 (has links)
The work of this thesis includes designs, molecular beam epitaxy (MBE) growths and optical study of electro-absorption modulator (EAM) structures. Three EAM structures are designed near 1.5 um : symmetric, asymmetric multiple quantum wells (MQWs) of TE polarization, and polarization insensitive MQWs. For symmetric and asymmetric MQWs simulation of TE polarization, their red-shift are 31 nm and 50 nm, respectively, as the electric field decrease from -40 kV/cm to -120 kV/cm. For polarization insensitive MQWs, we use the strained quantum-well concept to achieve same transition energy and absorption. After growth by MBE system, the samples were fabricated in mesa type by photolithography and wet etching. For symmetric and asymmetric quantum wells of TE polarization¡Gthe red-shift are 16 nm and 49 nm, respectively, as the bias decrease form 0-1 volt to 0-6 volt. Because of small ¡µn near subband transition energy, these two samples exhibit small chirp parameter. However, the photoluminescence (PL) and photocurrent spectra of these two ones were not near 1.5 um and obvious absorption edge. The possible reason is that the molecular beam flux have changed during growth. For polarization insensitive MQWs, the PL spectra shows 1494 nm, which only 25.6 nm differ from our design. Also, the photocurrent spectra of TE and TM polarization nearly exhibit same transition energy and have small chirp parameter.
34

Growth kinetics and doping of gallium nitride grown by RF-plasma assisted molecular beam epitaxy

Ptak, Aaron J. January 2001 (has links)
Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xvii, 161 p. : ill. Includes abstract. Includes bibliographical references (p. 154-161).
35

Process modeling of InAs/AISb materials for high electron mobility transisitors grown by molecular beam epitaxy

Triplett, Gregory Edward, January 2004 (has links) (PDF)
Thesis (Ph. D.)--School of Electrical and Computer Engineering, Georgia Institute of Technology, 2004. Directed by Gary S. May. / Includes bibliographical references (leaves 109-113).
36

Optical properties of GaSb/AlSb/InAs-based quasi-type I quantum structures /

Lee, Ka Yuk. January 2004 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 44-48). Also available in electronic version. Access restricted to campus users.
37

Characterization of as-grown and annealed narrow band gap nitrides grown by molecular beam epitaxy

Reifsnider, Jason Miles, Holmes, Archie L., January 2003 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Archie L. Holmes, Jr. Vita. Includes bibliographical references. Also available from UMI.
38

MBE-grown Fe ferromagnetic quantum dots /

So, Tak Ki. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 61-62). Also available in electronic version. Access restricted to campus users.
39

Anion exchange at the interfaces of mixed anion III-V heterostructures grown by molecular beam epitaxy

Brown, Terence D. January 2003 (has links) (PDF)
Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2004. / May, Gary, Committee Chair; Doolittle, William, Committee Member; Brown, April, Committee Member; Wang, Zhong Lin, Committee Member; Ralph, Stephen, Committee Member. Includes bibliography.
40

Heteroepitaxial growth of InN on GaN by molecular beam epitaxy /

Ng, Yee-fai. January 2002 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 102-106).

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