Charlotte K. Lowe-Ma

Evaluation of glass-forming potential of complex chalcogenides for long-wavelength infrared applications

LWIR-transmitting materials are of interest for medical, sensing, and communication applications where optical, mechanical and chemical stability during use are essential. Currently available materials are limited to crystalline chalcogenides and halides, chalcogenide glasses, and chalcohalide glasses whose long wavelength transmissivity is obtained at the expense of thermal and quite often chemical stability. This paper reviews preliminary results from an investigation of the glass forming tendencies of a group of compounds that have been chemically designed for optimal transparency in the 8 - 12 micrometers region and that also possess good mechanical and chemical stability.

Alternate Titanium Source Compounds for CVD of Ti/TiC Coatings

CVD experiments were conducted using (Me 3 SiCH 2 ) 4 Ti, Bis(2,4-dimethylpentadienyl) titanium, Cl 3 TiMe, (Me 3 SiCH 2 TiCl 3 to evaluate their potential as Ti precursor compounds. Only Me 3 SiCH 2 TiCl 3 was suitable for atmospheric CVD applications. Uniform thin films of polycrystalline TiC were deposited using Me 3 SiCH 2 TiCl 3 in an argon ambient between 700 °C and 800 °C. A mechanism involving initial loss of Me 3 SiCl to generate a titanium carbene intermediate is proposed. Thin films of TiC deposited on Si[111] were characterized using XRD and AES. Depth profile line shape analysis showed only TiC and elemental Si in the interfacial region. XRD indicates some titanium silicide is formed at 800 °C. In a hydrogen ambient, hydrogenolysis of the alkyl group occurs and very poor film growth results were obtained.

Pyrolysis Studies and Deposition of Sb Films Using the Novel Omvpe Source (I-Pr) 2 SbH

The novel antimony source compound di-isopropylantimony hydride, (i-Pr) 2 was synthesized and evaluated for use as a volatile Sb-source compound for low temperature growth of Sb-containing semiconductor materials. (i-Pr) 2 SbH was pyrolyzed in a horizontal atmospheric pressure organometallic vapor phase epitaxy (OMVPE) reactor using Arand H 2 as carrier gases. The gaseous exhaust products were analyzed by a residual gas analyzer. Complete pyrolysis of (i-Pr) 2 SbH in our OMVPE reactor occursaround 300°C and 350°C in Ar and H 2 , respectively. A comparison between the pyrolysis temperatures and pyrolysis byproducts with respect to a proposed decomposition mechanism of (i-Pr) 2 SbH is presented. Sb films were grown on Si(100) andSi(111) as low as 200° C. The Sb films were analyzed by Auger and X-ray diffraction. These polycrystalline Sb films were free of detectable carbon by AES. X-ray diffraction data indicated that these Sb films were highly oriented in the [000L] direction.