Radiation Defect-Induced Lattice Contraction of InP
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RADIATION DEFECT-INDUCED LATTICE CONTRACTION OF InP C.R. WIE• T. JONES,**T.A. TOMBRELLO,*T. VREELAND, JR. F. XIONG,*Z. ZHU,* G. BURNS*** AND F.H. DACOL*** * State University of New York at Buffalo, Dept. of Electrical and Computer Engineering, Amherst, N.Y. "**California Institute of Technology, 14260 Div. of Physics, Mathematics and Astronomy, and Engineering and Applied Sciences, Pasadena, CA 91125 ***IBM Thomas Watson Research Center, Yorktown Heights, New York 10598
ABSTRACT We studied the lattice strain induced in the MeV ion bombarded InP crystals and the annealing behaviors of lattice strain, Raman line shift, and linewidth. The lattice spacing for the planes parallel to the surface decreases as a result of irradiation, and amounts to a strain of -0.061% for (100) face, -0.056% for (110) face, and -0.050% for (111) face for 15 MeV Cl bombarded samples to a dose of 1.25E15 ions/cm2 . The negative lattice strain, Raman line shift, and line width completely recover at 450'C, and show a major recovery stage at 250'C - 350'C. INTRODUCTION InP is an important III-V compound for optoelectronic, photovoltaic, high-speed logic, and microwave devices. InP and alloys on InP substrates can be used to fabricate integrated electronic and electro-optic devices on the same chip for high-speed computer and communications applications. In spite of its potential, development of InP technology, and the materials study of InP has been less emphasized than GaAs [1]. It is partly due to their similar bandgaps, and that fabrication technology is easier for GaAs than for InP. Reported studies of the radiation-induced defects in InP include identification of PI- antisites [2], defect states [3-7], formation and annealing of defects [8] in electron-irradiated samples, deep and shallow levels [9] and photoconductivity [10] in light-ion bombarded InP, and annealing of electron traps in v-ray irradiated samples [11]. In MeV electron-irradiation studies, Levinson et al. found many electron traps with anomalously low introduction rates (10-4- 10-3cm-1) compared with GaAs (nl cm-1) and GaP (%O.i cm-1) [4]. Koyama et al. measured the introduction rate of a dominant electron trap in Y-ray irradiated samples (%0.05 cm-1), and they attributed the lower introduction rate in the electron-irradiated samples to a simultaneous annealing during the irradiation by beam-heating [11]. MeV ion implantation in III-V compounds is interesting because of its potential applications in device processing for such devices as buried channel CCDs, mixer diodes, vertical FETs and photodiodes [12]. Other applications include buried isolation layers, buried interconnects, and modifications of optical properties for III-V laser devices. MeV ion implantation also can be used to replace costly and time-consuming epitaxial processing [13]. In view of the above, we studied the effects on structural properties [14-16], and the phonon energy shifts [20,21] in GaAs bulk and epitaxial samples resulting from MeV ion implantation. In this paper, we present the experimental dat
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