Accession Number:

ADA289107

Title:

Low Temperature Deposition and Characterization of N- and P-Type Silicon Carbide Thin Films and Associated Ohmic and Schottky Contacts.

Descriptive Note:

Semiannual technical rept. 1 Jul-31 Dec 94,

Corporate Author:

NORTH CAROLINA STATE UNIV AT RALEIGH

Personal Author(s):

• Davis, Robert F.
• Nemanich, Robert J.

Report Date:

1994-12-01

Pagination or Media Count:

39.0

Abstract:

Exposure of heated 6H-SiC wafers to SiH4 contained both in a gas stream and an activated plasma was investigated for low temperature SiC cleaning and oxygen removal prior to thin film deposition. UPS revealed the first observation of surface states on the cleaned 6H-SiC surface. Monocrystalline epitaxial films of Beta3C-SiC111 and alpha6H-SiC0001 were grown on vicinal approx. 3.50 deg off0001 towards alpha6H-SiC0001 substrates via gas-source MBE from 1050 to 1250 deg C using Si2H6 and C2H4. Undoped films were n-type p-type films were achieved using Al evaporation during growth. The undoped 3C-SiC films grown on thin AIN buffer layers had carrier concentrations as low as 3x10 exp15cu cm. Extremely efficient activation of n-type Al dopants has been achieved. Initial attempts at n-type doping using NH3 are also described. Surfaces of 6H-SiC0001 homoepitaxial layers deposited on vicinal and on-axis 6H-SiC wafers by CVD have also been investigated using ultra-high vacuum scanning tunneling microscopy UHV STM. The vicinal surface showed strongly undulating step configurations. The on-axis surface possessed much wider terraces and much smoother step undulations. Step heights on both surfaces were 2.5 A corresponding to a single bilayer containing one Si and one C layer. After annealing at T110 deg C for 3-5 min. in UHV. selected terraces contained honeycomb-like regions most likely caused by the transformation to graphite as a result of Si sublimation.

Descriptors:

• *LOW TEMPERATURE
• *THIN FILMS
• *DEPOSITION
• *N TYPE SEMICONDUCTORS
• *SCHOTTKY BARRIER DEVICES
• *SILICON CARBIDES
• *P TYPE SEMICONDUCTORS
• BUFFERS
• ANNEALING
• ACTIVATION
• REMOVAL
• MICROSTRUCTURE
• LAYERS
• PHASE TRANSFORMATIONS
• PLASMAS(PHYSICS)
• FILMS
• EFFICIENCY
• SINGLE CRYSTALS
• CHARGE CARRIERS
• EPITAXIAL GROWTH
• GRAPHITE
• SUBSTRATES
• ELECTRICAL PROPERTIES
• ROOM TEMPERATURE
• OXYGEN
• CHEMISTRY
• ELECTRON BEAMS
• SURFACE PROPERTIES
• SUBLIMATION
• AXES
• DOPING
• EVAPORATION
• CURRENTS
• TRANSFORMATIONS
• ELECTRIC CONTACTS
• GAS FLOW

Subject Categories:

• Inorganic Chemistry
• Physical Chemistry
• Electrical and Electronic Equipment
• Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE