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The development of a self-consistent electrothermal transport model that coupled electrical and thermal transport equations and which could be applied to AlGaN/GaN device structures grown on the three different substrate materials such as SiC, Si, and sapphire is reported. The marked difference observed in the saturated current levels for AlGaN/GaN structures on SiC, Si, and sapphire substrates is directly related to the different self-heating levels that resulted from the different biasing conditions and the distinctive materials.

An InGaAlAs-based component and an InGaAsP-based component are integrated by using a butt-jointing process with in situ cleaning. The results have shown that InGaAlAs-InGaAsP hetero-material integrated devices can be used for next-generation high-speed data links.

A study was conducted to evaluate the electrostatic potential profile across the p-n junction of an AlGaAs/GaAs light-emitting diode (LED) with linearly graded triangular AlGaAs barriers using off-axis electron holography. Results suggest that electron holography measurements shared with modeling present device designers a helpful tool for analyzing doping profiles in complex heterostructures.

Low oxygen content (LOC) CuAl with no barrier metal (Ta) oxidation is obtained by using an oxygen absorption process that is based on metallurgical thermodynamic principles. The studies have shown that the LOC CuAl damascene interconnects (DDIs) have improved via reliability against both stress-induced voiding (SiV) and electromigration (EM), which is applicable for 45-nm-node LSI devices with 140-nm-pitch lines.

High-voltage GaN high-electron mobility transistors are prepared by using two types of heterostructures with different buffer layer structures and the effect of buffer layer structure on the crystal defect density in grown AlGaN/GaN heterostructure is examined. The results have shown that the dynamic on-resistance is increased with the edge dislocation density and is not affected by the screw dislocation density.

A series of high-mobility [Al.sub.0.12][In.sub.0.88]Sb/InSb heterostructures are grown by molecular beam epitaxy to examine the fabrication of micro-Hall magnetic field sensors. The results have shown that the utility of devices with larger devices has led to magnetic field detection in the pT range at low temperatures and sub-nT range even at room temperature.

The fabrication and optical and electrical properties of a modulation-doped multiquantum-well (MD-MQW) AlGaInP light-emitting diode (LED), grown by low-pressure metal-organic vapor-phase epitaxy (LP-MOVPE), are analyzed. The n-type MD-MQW LEDs are better than conventional undoped-MQW LEDs, which are attributed to the presence of the large number of mobile electrons in the MD-MQW structure.

n-Type and p-type dipoles are incorporated in TaN gate stacks by forming terbium (Tb)- and aluminum (Al)-based interlayers (ILs), respectively, and a detailed study is conducted on the effect of combining n-type and p-type dipoles into the same TaN gate stack for metal gate work function tunability. The concept of manipulating interface dipoles of opposing polarity for metal gate work function tunability has opened new ways for achieving multiple work functions by using a single metal gate and a simple integration scheme.

Proton implantation is used for fabricating AlGaN/GaN high electron mobility transistors (HEMTs) and the breakdown voltage of these HEMTs is increased without sacrificing dc characteristics. The increase of the breakdown voltage is because of the expansion of the depletion region under the two-dimensional (2-D) electron gas (2-DEG) channel.

A self-consistent extraction method is presented for coplanar waveguide (CPW) probed AlGaN high-electron mobility transistors (HEMTs). Findings reveal the achievement of consistent results for both small- and large periphery AlGaN HEMTs.

An ensemble two-dimensional (2-D) Monte Carlo simulator is used for analyzing the noise performance of InAlAs/InGaAs double-gate (DG) and standard high-electron-mobility transistors (HEMTS). Better noise behavior is observed in the DG-HEMT as compared to the single-gate (SG) device.

Long term characteristic stabilities of metal-insulator-metal (MIM) capacitors with HfAlO dielectric under constant-voltage stress (CVS) are examined. Findings reveal a gradual increase in relative dielectric constant, dielectric loss, temperature coefficient of capacitance and frequent coefficient of capacitance.

The magnetic and electronic properties of the quaternary [Co.sub.2][[Y.sub.1-x][Y.sub.x]*]Z (Z = Al, Ga, Si, Ge, or Sn) Heusler compounds studied to complement the doping and disorder in [Co.sub.2]MnZ compounds. The results have shown that the presence of Fe has reduced the majority density of states at the Fermi level and it can even destroy half-metallicity when combined with an element belonging to the Si column.

A study of the evolution of microplasmas produced on aluminum alloy surface at ambient air pressure by 266-nm 10-ns laser pulses with energies of 3 to 100 [micro]J (2 to 68 GW/[cm.sup.2]) is carried out. Gated photography with a minimum width of 5 ns is used to investigate the plasma evolution. Plasma emission and plasma distances from the sample surface are investigated as a function of time. Pulse energy has a strong effect on plasma emission particularly at short delay times. The experimental results are compared with a simplified model of plume expansion. Index Terms--Ablation, imaging, laser-induced breakdown spectroscopy (LIBS), plasma expansion.

Tunneling results for junctions comprising Mn doped Al films produced by sputter deposition, with Mn concentrations in the range of 0-5000 ppm are presented. The results demonstrate that Al-Mn alloys can serve both as superconductors with critical temperatures reduced from that of Al and as normal metals.

Specific heat and temperature-dependent magnetization M(T) and resistivity p(T) with field and current, respectively, parallel and perpendicular to the c axis is investigated on a single crystal of Y[Mn.sub.4][Al.sub.8]. It is found that, while the temperature dependence of dc magnetization is similar to that for the polycrystalline samples without a noticeable anisotropy, there is an interesting anisotropy in the electronic transport.

Several nonlinear ultrasonic studies are conducted to explain the variation in strength caused by the precipitation characteristics of the system. The strength property is shown to be highly dependent on the precipitation phase transitions.

Several first-principles calculations are conducted to explain the magnetic properties exhibited by the [Ga.sub.x][Mn.sub.1-x]N, [A.sub.x][Mn.sub.1-x]N, and [In.sub.x][Mn.sub.1-x]N ternary systems. The magnetic moment of these alloys is mainly shown to be a result of the presence of the Mn atom.

Several steady state and dynamic spectral studies are conducted to explain the characteristics of energy transfer exhibited by the (Nd, Yb):[Y.sub.3][Al.sub.5][O.sub.12] transparent ceramics. The Nd-Yb energy is shown to be highly dominated by the dipole-dipole interactions.