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Electron mobility, Hall scattering factor, and sheet conductivity in AlGaN/AlN/GaN heterostructures J. Appl. Phys. 110, 113713 (2011) Reduction of the potential energy barrier and resistance at wafer-bonded n-GaAs/n-GaAs interfaces by sulfur passivation J. Appl. Phys. 110, 104903 (2011) Diameter reduction of nanowire tunnel heterojunctions using in situ annealing Appl. Phys. Lett. 99, 203101 (2011) Substrate nitridation induced modulations in transport properties of wurtzite GaN/p-Si (100) heterojunctions grown by molecular beam epitaxy J. Appl. Phys. 110, 093718 (2011) Characteristics of a-GaN films and a-AlGaN/GaN heterojunctions prepared on r-sapphire by two-stage growth process

In the last years, silicon micromachining techniques based on high aspect ratio reactive ion etching with gas chopping have been developed. There the gas flow of etching and deposition gas precursors is chopped which results in controllable sidewall passivation and high anisotropy. However, the rippled sidewalls are a serious limit for various applications. We report on the development of a novel gas chopping etching technique (GCET) process in order to achieve a smooth (rippled free) sidewall surface. As the direct etch mask, we used a 1 or 2-μm-thick resist layer, which was lithographically patterned. The novelty of the process consists in the replacing of the isotropic etching step by an anisotropic etching step. In this way we omit the main source for sidewall ripples. GCET combined with inductively coupled plasmas and fluorine chemistry provide very high etch rates and good control of the sidewall slope. These techniques also can be applied to conventional reactive ion etching equipment with Cl or F based plasma chemistry. However, the techniques used in this study have lower selectivity (in range of 30) than the conventional GCET. A SiON/Si selectivity as high as 50 has been achieved.

In this study, the interface adhesion and mechanical strength of wafer bonded GaAs/GaAs and GaAs/InP semiconductors, each of (100) face, were characterized by combining the measurements of interface fracture energy γo and lap shear strength Es. The relations between the interface adhesion and annealing processes for four different types of bonding configurations, i.e., antiphase bonding, in-phase bonding, and twist bonding with 5° and 30° misalignments, were systematically studied. The surface free energy γα-GaAs/oxide (0.11–0.28 J/m2) of amorphous α-GaAs/oxide mixture was estimated based upon the reported surface free energy γc-GaAs (0.63 J/m2) of crystalline [100] GaAs and measured overall interface fracture energy γtotal (0.525 J/m2) of GaAs/GaAs bonded wafers. The micromorphologies of the bonded and debonded wafer interfaces were characterized by atomic force microscopy (AFM) and transmission electron microcopy (TEM). The interface microfailure mechanism of directly bonded GaAs wafers was proposed based on AFM and TEM microstructural analysis.

Based upon temporal measurements of interface electrical conductivity from current–voltage characterization and interface micromorphologies from transmission electron microcopy, a kinetic analysis of the thermally induced interfacial transformation process of GaAs/GaAs semiconductor interfaces fabricated by wafer bonding technology is performed. The activation energy required for the overall interface transformation that involves defect and atomic diffusion was determined to be 0.75 eV. A physical model of this transformation process is proposed.

Structural and vibrational properties of molecular beam epitaxy grown cubic (Al, Ga) Material integrations of GaN/GaN and Al 0.25 Ga 0.75 N/GaN semiconductors through wafer bonding technology were reported in this work. The wafer surface and interface microstructures were characterized by scanning electron microscopy and energy dispersive x-ray spectroscopy. The interface adhesion ͑bonding strength͒ was estimated based upon the interface fracture energy ␥ o measured by double-cantilever beam technique. The interface adhesion properties of several different wafer-bonded III-V semiconductors were also compared. By comparing the atomic chemical bond energy E o with the measured interface fracture energy ␥ o , the bondability of a few major III-V semiconductors was analyzed.

In this paper, through the morphological study of surface-treated samples and by using the well-known Halpin-Tsai equations, the aspect ratio and the elastic modulus of the shear-induced fibers from a thermotropic liquid crystalline polymer (LCP, Vectra A950) in a polycarbonate (PC) matrix were determined. Based on Cox's classic theories about the development of disperse liquid drops in suspending medium, the deformation mechanism of the LCP phase in the thermoplastic matrix was quantitatively or semi-quantitatively studied. The relationships among the viscosity ratio of LCP and PC, Weber number and the fiber development are given.

In this paper, the synthesis and characterization of a new family of aliphatic / aromatic copolyester resins is described. This new resin is derived from a two component oligomeric system consisting of a mixture of Novolac acetates and several specially designed oligomers with carboxylic acid end groups. In this new material, aliphatic units have been incorporated into the oligomers in order to reduce the processing temperature. When used as an adhesive, the new resin offers good lap shear strength of about 14 MPa (2000 psi) at room temperature and retains useful properties to 80°C–100°C. This new system provides good thermal stability, environmental resistance and char yield of 25–40%.