Load deflection analysis for determining mechanical properties of thin films with tensile and compressive residual stresses

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995.Includes bibliographical references (leaves 24-25).by Mayank T. Bulsara.M.S

Phase-controlled, heterodyne laser-induced transient grating measurements of thermal transport properties in opaque material

The methodology for a heterodyned laser-induced transient thermal grating technique for non-contact, non-destructive measurements of thermal transport in opaque material is presented. Phase-controlled heterodyne detection allows us to isolate pure phase or amplitude transient grating signal contributions by varying the relative phase between reference and probe beams. The phase grating signal includes components associated with both transient reflectivity and surface displacement whereas the amplitude grating contribution is governed by transient reflectivity alone. By analyzing the latter with the two-dimensional thermal diffusion model, we extract the in-plane thermal diffusivity of the sample. Measurements on a 5 {\mu}m thick single crystal PbTe film yielded excellent agreement with the model over a range of grating periods from 1.6 to 2.8 {\mu}m. The measured thermal diffusivity of 1.3 \times 10-6 m2/s was found to be slightly lower than the bulk value.Comment: 19 pages, 6 figure

Lifetime of sub-THz coherent acoustic phonons in a GaAs-AlAs superlattice

We measure the lifetime of the zone-center 340 GHz longitudinal phonon mode in a GaAs-AlAs superlattice excited and probed with femtosecond laser pulses. By comparing measurements conducted at room temperature and liquid nitrogen temperature, we separate the intrinsic (phonon-phonon scattering) and extrinsic contributions to phonon relaxation. The estimated room temperature intrinsic lifetime of 0.95 ns is compared to available calculations and experimental data for bulk GaAs. We conclude that ∼0.3 THz phonons are in the transition zone between Akhiezer and Landau-Rumer regimes of phonon-phonon relaxation at room temperature.United States. Dept. of Energy. Office of Basic Energy Sciences (Award DE-SC0001299)United States. Dept. of Energy (Grant DE-FG02-00ER15087

Compound Semiconductor Materials and Devices

Contains table of contents for Part I, table of contents for Section 1, reports on fourteen research projects and a list of publications.Defense Advanced Research Projects Agency/National Center for Integrated Photonics TechnologyFannie and John Hertz Foundation Graduate FellowshipJoint Services Electronics Program Grant DAAH04-95-1-0038National Science Foundation Graduate FellowshipNTT CorporationNational Science FoundationU.S. Navy - Office of Naval ResearchToshiba CorporationAT&T Bell Laboratories Graduate Fellowshi

Compound Semiconductor Materials and Devices

Contains table of contents for Part I, table of contents for Section 1, an introduction, reports on fourteen research projects and a list of publications.Defense Advanced Research Projects Agency/National Center for Integrated Photonics TechnologyJoint Services Electronics Program Grant DAAH04-95-1-0038MIT Lincoln LaboratoryNational Science Foundation Graduate FellowshipU.S. Navy - Office of Naval ResearchAT&T Bell Laboratories FellowshipU.S. Army - Ft. MeadeNTT CorporationNational Science FoundationLockheed-Martin Corporatio

Materials issues with the integration of lattice-mismatched In Inx̳Ga₁âx̳As devices on GaAs

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1998.In title on t.p., double-underscored characters appear as subscript.Includes bibliographical references (p. 170-178).by Mayank T. Bulsara.Ph.D

Materials properties and dislocation dynamics in InAsP compositionally graded buffers on InP substrates

The properties of InAs [subscript x]P1[subscript −x] compositionally graded buffers grown by metal organic chemical vapor deposition are investigated. We report the effects of strain gradient (ε/thickness), growth temperature, and strain initiation sequence (gradual or abrupt strain introduction) on threading dislocation density, surface roughness, epi-layer relaxation, and tilt. We find that gradual introduction of strain causes increased dislocation densities (>10[superscript 6]/cm[superscript 2]) and tilt of the epi-layer (>0.1°). A method of abrupt strain initiation is proposed which can result in dislocation densities as low as 1.01 × 10[superscript 5] cm[superscript −2] for films graded from the InP lattice constant to InAs [subscript 0.15]P[subscript 0.85]. A model for a two-energy level dislocation nucleation system is proposed based on our results.National Science Foundation (U.S.) (MIT MRSEC Program Award No. DMR-08-19762)United States. Dept. of Energy (Office of Science, Basic Energy Sciences under award No. DE-FG02-09ER46577)United States. Dept. of Energy (Solid State Solar Thermal Energy Conversion Center, an Energy Research Frontier Center, Award No. DE-FG02-09ER46577

High mobility In[subscript 0.53]Ga[subscript 0.47]As quantum-well metal oxide semiconductor field effect transistor structures

In this paper, we demonstrate high electron mobility In[subscript 0.53]Ga[subscript 0.47]As quantum-well metal oxide semiconductor field effect transistor(MOSFET)structures. The Al[subscript 2]O[subscript 3] (gate dielectric)/In[subscript 0.53]Ga[subscript 0.47]As-In[subscript 0.52]Al[subscript 0.48]As (barrier)/In[subscript 0.53]Ga[subscript 0.47]As (channel) structures were fabricated, and the mobility was obtained by Hall measurements. The structures with in-situchemical vapor deposition(CVD)Al[subscript 2]O[subscript 3] displayed higher mobility than identical structures fabricated with in situ atomic layer deposition Al[subscript 2]O[subscript 3], which indicates that CVD process resulted in a lower Al[subscript 2]O[subscript 3]/In[subscript 0.53]Ga[subscript 0.47]As interfacial defect density. A gate bias was applied to the structure with CVDAl[subscript 2]O[subscript 3], and a peak mobility of 9243 cm[superscript 2]/V s at a carrier density of 2.7 × 10[superscript 12] cm[superscript −2] was demonstrated for the structure with a 4 nm In[subscript 0.53]Ga[subscript 0.47]As-In[subscript 0.52]Al[subscript 0.48]As barrier. A model based on internal phonon scattering and interfacial defect coulomb scattering was developed to explain the experimental data and predict the mobility of In[subscript 0.53]Ga[subscript 0.47]As MOSFETstructures.Semiconductor Research Corporation. Center for Materials, Structures and Device

Controlling Epitaxial GaAs[subscript x]P[subscript 1-x]/Si[subscript 1-y]Ge[subscript y] Heterovalent Interfaces

High quality epitaxial growth of GaAsP on SiGe templates would allow access to materials and band gaps that would enable novel, high performance devices on Si. However, GaAsP/SiGe interface engineering has proved to be very complex. In this paper, we explore the effects of strain at the heterovalent interface between GaAsP and SiGe alloys on the overall defect morphology.United States. Army Research Office (Grant W911NF-09-1-0222