R. T. Zhang

Silicon-on-insulator with hybrid orientations for heterogeneous integration of GaN on Si (100) substrate

Heterogeneous integration of materials pave a new way for the development of the microsystem with miniaturization and complex functionalities. Two types of hybrid silicon on insulator (SOI) structures, i.e., Si (100)-on-Si (111) and Si (111)-on-Si (100), were prepared by the smart-cut technique, which is consist of ion-slicing and wafer bonding. The precise calculation of the lattice strain of the transferred films without the epitaxial matching relationship to the substrate was demonstrated based on X-ray diffraction (XRD) measurements. The XRD and Raman measurement results suggest that the transferred films possess single crystalline quality. With a chemical mechanical polishing (CMP) process, the surface roughness of the transferred thin films can be reduced from 5.57 nm to 0.30 nm. The 4-inch GaN thin film epitaxially grown on the as-prepared hybrid SOI of Si (111)-on-Si (100) by metalorganic chemical vapor deposition (MOCVD) is of improved quality with a full width at half maximum (FWHM) of 672.54 arcsec extracted from the XRD rocking curve and small surface roughness of 0.40 nm. The wafer-scale GaN on Si (111)-on-Si (100) can serve as a potential platform for the one chip integration of GaN-based high electron mobility transistors (HEMT) or photonics with the Si (100)-based complementary metal oxide semiconductor (CMOS).Heterogeneous integration of materials pave a new way for the development of the microsystem with miniaturization and complex functionalities. Two types of hybrid silicon on insulator (SOI) structures, i.e., Si (100)-on-Si (111) and Si (111)-on-Si (100), were prepared by the smart-cut technique, which is consist of ion-slicing and wafer bonding. The precise calculation of the lattice strain of the transferred films without the epitaxial matching relationship to the substrate was demonstrated based on X-ray diffraction (XRD) measurements. The XRD and Raman measurement results suggest that the transferred films possess single crystalline quality. With a chemical mechanical polishing (CMP) process, the surface roughness of the transferred thin films can be reduced from 5.57 nm to 0.30 nm. The 4-inch GaN thin film epitaxially grown on the as-prepared hybrid SOI of Si (111)-on-Si (100) by metalorganic chemical vapor deposition (MOCVD) is of improved quality with a full width at half maximum (FWHM) of 672.54 ar...

Investigation on thermodynamics of ion-slicing of GaN and heterogeneously integrating high-quality GaN films on CMOS compatible Si(100) substrates

Die-to-wafer heterogeneous integration of single-crystalline GaN film with CMOS compatible Si(100) substrate using the ion-cutting technique has been demonstrated. The thermodynamics of GaN surface blistering is in-situ investigated via a thermal-stage optical microscopy, which indicates that the large activation energy (2.5 eV) and low H ions utilization ratio (~6%) might result in the extremely high H fluence required for the ion-slicing of GaN. The crystalline quality, surface topography and the microstructure of the GaN films are characterized in detail. The full width at half maximum (FWHM) for GaN (002) X-ray rocking curves is as low as 163 arcsec, corresponding to a density of threading dislocation of 5 × 107 cm−2. Different evolution of the implantation-induced damage was observed and a relationship between the damage evolution and implantation-induced damage is demonstrated. This work would be beneficial to understand the mechanism of ion-slicing of GaN and to provide a platform for the hybrid integration of GaN devices with standard Si CMOS process.

The nucleus-nucleus scattering in transfer ionization of helium by He2+ impact

We have performed kinematically complete measurement on transfer ionization of He by 50 keV/u He2+ impact. The data were analyzed in terms of Dalitz spectrum. We evaluated the role of three particles interactions and found that the main momentum exchange occurs between the projectile and the recoil ion. This result indicate that the nucleus-nucleus high order interaction could not be overlooked in transfer ionization collision dynamics of atom by intermediate energy ion impact.

The fragmentation of neon dimer induced by low energy O6+ ions

We have investigated the fragmentation channels Ne+-Ne+ and Ne2+-Ne+ from Ne2 dimer induced by O6+ ions at impact energy of 15 keV/u. The Ne+-Ne+ fragmentation channel mainly results from three pathways: the interatomic coulombic decay of Ne2+(2p4)-Ne initial state, the direct columbic explosion and the radiation charge transfer. Nevertheless, the fragmentation channel Ne2+-Ne+ is predominant by the direct coulombic explosion.

Experimental investigation of state selective single-electron capture in 120 keV Ar8+ - He collisions

The longitudinal and the transversal momentum of recoil ions were measured for single electron capture in 120 keV Ar8+ - He collisions, using the reaction microscope techniques. The characteristics of the radial and the rotational coupling were identified for 1s to 4s and 1s to 4p sub-state selectivity.

An experimental investigation of the dissociative ionization process of argon cluster ions induced by electron impact

Utilizing the Cold Target Recoil Ions Momentum Spectrometer (COLTRIMS), dissociative ionization of argon cluster was experimentally investigated by electron impact. The recoil ions produced both in the pure ionization process and the dissociative ionization channels are measured with collision energies from 100 and 1000 eV. The ratios of the dimer ions from pure ionization (Ar2P+) and the dimer ions from small cluster dissociation (Ar+2D) to the atomic argon ion (Ar+) in different stagnation pressures were obtained.

Dynamics of transfer ionization process in p-He collisions at intermediate energies

Using the reaction microscope technique, we have performed a kinematically complete experiment on transfer ionization in 50 to 100 keV proton-helium collisions. A careful inspect on the momentum balance provides insight into the dynamics of the transfer ionization process.

The target effect in transfer ionization in proton-helium and neon collisions at intermediate energies

The velocity distribution of emitted electrons in the transfer ionization (TI) in p-He and p-Ne collisions had been measured at projectile velocity Vp=2 a.u. The characteristics of electrons emission in the scattering plane is significant different from that observed in the TI of He2+-He collision (L. Schmidt et al 2007 Phys. Rev. A 76 012703-1). The mechanism leading to the ejection of electrons has still not been completely understood.

Image of electron emission in He2+-He collisions at intermediate energies

The velocity distributions of electrons produced in the transfer ionization (TI) in He2+ - He collision at projectile velocities Vp = 1.41 and 1.72a.u. have been measured. The characteristic of electron emission in the scattering plane is totally different from that observed in single ionization of the same collision system at Vp = 1.63 (Abdallah et al 1997 Phys. Rev. A 56 2000), and it has not been completely understood.

Experimental investigation of single capture with single ionization in 30keV/u He2+ on argon collisions

Applying reaction microscope, electron emission from single capture with simultaneous single ioniza-tion in 30keV/u He2+ on argon collisions was studied. Intensive peak near zero energy and electron-capture-to-the-continuum peak are obtained. It is demonstrated that low energy electrons mainly result from direct transfer ionization.