Group IV semiconductor surface chemistry: A multiple internal reflection infrared spectroscopy study

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5721463

Lu, G Q

The adsorption of Si[sub 2]H[sub 6], Ge[sub 2]H[sub 6], and hydrogen (atoms) on Ge(111) and Si(100) surfaces are characterized by using multiple internal reflection infrared spectroscopy (MIRIRS). The inherent high resolution or infrared spectroscopy and the application of polarized light enable the detection of important modes for resolving the structure of surface species. The choice of Ge as substrate has extended the low frequency limit for MIRIRS to below 700 cm[sup [minus]1] (in comparison to that of Si at 1450 cm[sup [minus]1]). The vibrational modes in this low frequency region are used to uniquely measure the extent of Si[sub 2]H[sub 6] and Ge[sub 2]H[sub 6] dissociation on Ge(111). Si[sub 2]H[sub 6] and Ge[sub 2]H[sub 6] interact similarly with the Ge(111) surface. Molecular adsorption is the dominant process below 120K. Complete dissociation occurs above 150K to produce adsorbed trihydrides, SiH[sub 3] and GeH[sub 3], respectively. Adsorbed SiH[sub 3] decomposes at temperatures [ge] 200K to form SiH[sub 2], SiH and GeH, while surface GeH[sub 3] decomposition produces only GeH[sub 2] and GeH. Decomposition of all surface hydrides occurs by 600K. The adsorption of atomic hydrogen on Ge(111) leads to the production of GeH[sub 3], GeH[sub 2] and GeH at low temperatures ([le]200K), and strictly monohydrides at temperatures [ge]400K. Atomic hydrogen occupies primarily a single adsorption site at 500K, while a variety of adsorption sites are populated at lower adsorption temperatures. The reaction of H atoms with Si(100) - 2 [times] 1 produces Si(100) - 2 [times] 1:H, 3 [times] 1:H, and 1 [times] 1:H, sequentially, depending on the exposure and adsorption temperatures. The highly repulsive interaction between SiH[sub 2] groups prohibits the formation of a pure 1 [times] 1 dihydride phase, and induces the preferential formation of SiH[sub 3] at low temperatures ([le]150K).

• Research Organization: California Univ., San Diego, La Jolla, CA (United States)
• OSTI ID: 5721463
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical & Spectral Procedures
ABSORPTION SPECTROSCOPY
DISSOCIATION
ELEMENTS
ENERGY LEVELS
EXCITED STATES
GERMANIUM
GERMANIUM COMPOUNDS
GERMANIUM HYDRIDES
HYDRIDES
HYDROGEN COMPOUNDS
METALS
MILLER INDICES
MOLECULAR STRUCTURE
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
REFLECTION
SEMIMETALS
SILANES
SILICON
SILICON COMPOUNDS
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
VIBRATIONAL STATES