Robert W. Gedridge

Low temperature MOCVD growth of V/VI materials via a Me 3 SiNMe 2 elimination reaction

The reactive precursors M(NMe/sub 2/)/sub 3/ (M=Sb, Bi) and (Me/sub 1/Si)/sub 2/Te were used to deposit films of M/sub 2/Te/sub 3/ (M=Sb, Bi) on Si(111) cut 4/spl deg/ off-axis, GaAs(100), and Kapton substrates between 25/spl deg/C and 150/spl deg/C in a low pressure MOCVD reactor. The film growth process is a novel N,N-dimethylamino-trimethylsilane (Me/sub 3/SiNMe/sub 2/) elimination reaction and not pyrolysis reactions employed in conventional MOCVD techniques. X-ray diffraction data show the crystalline quality and orientation of the resulting polycrystalline films were dependent on the substrate structure and growth temperature. Amorphous films were deposited below 50/spl deg/C. Films deposited at 75/spl deg/C for Sb/sub 2/Te/sub 3/ and 125/spl deg/C for Bi/sub 2/Te/sub 3/ were highly oriented with the (015) reflection plane parallel to the substrate surface. Films of Sb/sub 2/Te/sub 3/ deposited at 150/spl deg/C were highly oriented with the [00l] reflection planes parallel to the substrate surface. The electrical properties and composition of Bi/sub 2/Te/sub 3/ films deposited at 125/spl deg/C on Kapton were independent of the V/VI precursor ratio used. Variation in the composition of a Sb/sub x/Bi/sub 2-x/Te/sub 3/ ternary film across the susceptor was observed due to differences in the reaction kinetics for formation of Sb/sub 2/Te/sub 3/ and Bi/sub 2/Te/sub 3/. This unique deposition reaction provides an alternative route to prepare group V chalcogenide materials which have potential applications in solar cells, reversible optical storage, and thermoelectrics.

Chemical beam epitaxy of InP without precracking using tertiarybutylbis(dimethylamino)phosphine

Abstract For the first time, single crystalline layers of indium phosphide (InP) have been grown by the chemical beam epitaxy (CBE) technique without thermally precracking the phosphorus (P) source. This was accomplished using a novel P precursor, tertiarybutylbis(dimethylamino)phosphine (TBBDMAP). For a constant input V III ratio of 7.2, InP growth was studied for growth temperatures from 450 to 530°C. At 450°C, the surface was indium rich due to the incomplete pyrolysis of TBBDMAP. At 480 and 510°C, InP epilayers were successfully grown without precracking the TBBDMAP. An indium-rich surface was also observed at 530°C using this input V III ratio due to the high rate of phosphorus desorption. At growth temperatures of 480 and 510°C, the effect of the cracker cell temperature on the InP growth rate was studied.

Decomposition Mechanisms of Antimony Source Compounds for Organometallic Vapor-Phase Epitaxy

The decompositions of tertiary stibines (R 3 Sb, R = methyl, vinyl, isopropyl) were studied in an atmospheric pressure flow tube reactor, using D 2 and He as carrier gases. D 2 was used to isotopically label the byproducts in order to elucidate the pyrolysis mechanism. The exhaust products were analyzed by a time-of-flight mass spectrometer. The decomposition of these tertiary stibines in the presence of group Ill precursors was studied in order to simulate the conditions of organometallic vapor phase epitaxial growth. A comparison between the pyrolysis temperatures, decomposition mechanisms, and surface area effects of these Sb source compounds is presented.

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.