B-doped fully strained Si{sub 1{minus}{ital x}}Ge{sub {ital x}} layers grown on Si(001) by gas-source molecular beam epitaxy from Si{sub 2}H{sub 6}, Ge{sub 2}H{sub 6}, and B{sub 2}H{sub 6}: Charge transport properties
- Materials Science Department, Engineering Science Laboratory and the Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)
B-doped Si{sub 1{minus}{ital x}}Ge{sub {ital x}} layers with Ge fractions, determined by Rutherford backscattering spectroscopy, ranging from 0 to 0.28 and B concentrations, from quantitative secondary-ion spectroscopy measurements, between 5{times}10{sup 16} and 4{times}10{sup 19} cm{sup {minus}3} were grown on Si(001) at temperatures {ital T}{sub {ital s}}=475{endash}575{degree}C by gas-source molecular beam epitaxy from Si{sub 2}H{sub 6}, Ge{sub 2}H{sub 6}, and B{sub 2}H{sub 6}. Film thicknesses ranged from 200 nm for alloys with {ital x}=0.28 to 800 nm with {ital x}=0.05 to 1.4 {mu}m for Si. Structural analyses by high-resolution x-ray diffraction and reciprocal lattice mapping combined with transmission electron microscopy showed that all films were fully strained, with measured relaxations of only {approx_equal}4{times}10{sup {minus}5}, and exhibited no evidence of dislocations or other extended defects. The hole conductivity mobility {mu}{sub {ital c},{ital h}} in these layers increased continuously with increasing Ge concentrations, whereas the Hall mobility decreased yielding a Hall scattering factor that ranged from 0.75 for Si to 0.26 for Si{sub 0.72}Ge{sub 0.28} but was not strongly affected by B concentration. {mu}{sub {ital c},{ital h}}, with {ital C}{sub B}=2{times}10{sup 18} cm{sup {minus}3}, varied from 110 cm{sup 2}V{sup {minus}1}s{sup {minus}1} for Si{sub 0.95}Ge{sub 0.05} to 158 cm{sup 2}V{sup {minus}1}s{sup {minus}1} for Si{sub 0.72}Ge{sub 0.28}, compared to 86 cm{sup 2}V{sup {minus}1}s{sup {minus}1} for Si, in good agreement with Boltzmann transport model calculations accounting for changes in the valence-band structure due to the effects of both alloying and biaxial in-plane compressional strain. {copyright} {ital 1996 American Institute of Physics.}
- Research Organization:
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- DOE Contract Number:
- AC02-76ER01198
- OSTI ID:
- 383739
- Journal Information:
- Journal of Applied Physics, Vol. 80, Issue 8; Other Information: PBD: Oct 1996
- Country of Publication:
- United States
- Language:
- English
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