Mechanism of carbon incorporation during GaAs epitaxy

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States)

DOI:https://doi.org/10.1116/1.578320· OSTI ID:6266280

Creighton, J R; Bansenauer, B A ^[1]; Huett, T; White, J M ^[2]

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1. Department 1126, Sandia National Laboratories Albuquerque, New Mexico 87185 (United States)
2. Department of Chemistry, University of Texas Austin, Texas 78712 (United States)

The use of trimethylgallium (TMGa) as the gallium source during epitaxial growth of GaAs often leads to high levels of carbon incorporation. Using temperature programmed desorption, high-resolution electron energy loss spectroscopy (HREELS), and static secondary ion mass spectroscopy (SSIMS), we have identified a likely carbon incorporation pathway initiated by methyl group dehydrogenation. Methyl group dehydrogenation is evidenced by a small amount of hydrogen evolution around 430 [degree]C. Extended TMGa exposures in this temperature regime yield substantial coverages of methylene (CH[sub 2]) adsorbate that is detected by HREELS and SSIMS. The CH[sub 2] adsorbate undergoes further reaction at higher temperature, yielding acetylene (C[sub 2]H[sub 2]), H[sub 2], and CH[sub 3] radicals as desorption products at [similar to]550 [degree]C. All of these products can be attributed to a mechanism involving CH[sub 2] dehydrogenation, hydrogenation, and recombination reactions. The rate of CH[sub 3] dehydrogenation is consistent with carbon doping levels typically obtained by metalorganic molecular beam epitaxy (MOMBE) and related techniques. High temperature exposure to arsine (AsH[sub 3]) consumes the CH[sub 2] adsorbate, apparently by hydrogenating them back to CH[sub 3] groups that then desorb. This observation explains why carbon doping is lower during atomic layer epitaxy as compared to MOMBE.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6266280
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States), Journal Name: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States) Vol. 11:4; ISSN 0734-2101; ISSN JVTAD6
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
ALKYL RADICALS
ALLOYS
ARSENIC COMPOUNDS
ARSENIDES
CARBON ADDITIONS
CHEMICAL REACTIONS
DEHYDROGENATION
ELECTRON SPECTROSCOPY
ENERGY-LOSS SPECTROSCOPY
EPITAXY
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
MASS SPECTROSCOPY
METHYL RADICALS
MOLECULAR BEAM EPITAXY
PNICTIDES
RADICALS
SPECTROSCOPY