Formation of a buried soft layer in SiC for compliant substrate by ion implantation

Radiation damage and its removal have been studied in ion implanted 6H-SiC by Rutherford backscattering/Channeling (RBS). They have implanted Ga and Ti at 800 C using doses of 1 {times} 10{sup 16} to 2 {times} 10{sup 17} cm{sup {minus}2}. The implanted samples have been subsequently annealed at 1,050 C, and then at 1,400 C for 30 sec to study the removal of damage produced during implantation. The energies of implanted species have been chosen to obtain 20--40 nm projected ranges to form a buried metallic or graphitic layer. No significant damage removal has been observed after 1,050 C anneal, however 1,400 C annealing of 40 and 120 keV Ga implanted samples (fluence 2 {times} 10{sup 16} cm{sup {minus}2}) resulted in significantly less damage as can be observed from RBS/Channeling data. In the case of Ti implanted samples annealing led to an appreciable increase in the channeled backscattering yield, which might be due to the formation of some new phase (e.g., TiSi or TiSi{sub 2}) and may be related to distortions of the existing lattice

Ion implantation of epitaxial GaN films: damage, doping and activation

Single-crystal GaN films grown on AlN buffer layers previously deposited on 6H-SiC(0001) were studied for radiation damage and its recovery using Rutherford backscattering/channeling, photoluminescence, and cross-sectional TEM. The highest fluence of (1e15 cm{sup -2}) 110 keV Mg and 160 keV Si produced little damage at implantation temperature 550 C. RT damage was higher for same fluences compared to 550 C implantation. The damage was partially annealed by RTA at 1000 C, however, this was not enough to recover the PL signal even for the lowest fluence (1e14 cm{sup -2}). XTEM of as-implanted samples revealed small clusters of defects extended beyond the projected ion range. To recover damage completely, perhaps one needs to go either much higher RTA temperature and/or implant samples in a smaller fluence increment and anneal in between implants to recover the damage

Precise Chemical Analysis Development for Si and GaAs Surfaces

Precise chemical analysis (PCA) was developed to allow the study of non-interconnected atoms on crystalline semiconductor surfaces, such as those produced during rapid thermal processing (RTP) of silicon and electron beam lithography on gallium arsenide (GaAs). The PCA method is based on selectively dissolving the different components present on the semiconductor surface using preferential etchant solutions. After etching, the etchant solution, containing the etched component, is analyzed by a photometric technique. In this paper, we present photometric measurements of the amount of “free” (non-interconnected) atoms that remain on semiconductor surfaces following electron beam and RTP processing. In this context, “free” atoms are those presenting in any form other than crystalline GaAs or Si, for instance, those in the form of surface oxides. Using the PCA method, free Ga and As were detected on GaAs surfaces after electron beam lithography. Free silicon, boron and phosphorous atoms were found on silicon surfaces after RTP. The concentration of boron diffused into a silicon wafer during RTP was also carried out by means of slight surface etching. We estimate the accuracy of this PCA method at 2% for Ga and 5% for all other elements

Dielectric rod waveguide as an enabling technology for THz frequencies

A dielectric rod waveguide (DRW) made of high-dielectric-constant material such as sapphire, GaAs or Si has in the past been shown to have low transmission loss and good matching with a rectangular metal waveguide at millimetre wavelengths. Also various passive components have been demonstrated. Recently, it has been demonstrated that a single DRW antenna works well over several rectangular waveguide bands even up to 1 THz. Also first attempts have been made to integrate a photo mixer with a DRW waveguide to produce an effective THz source