Sputtering induced changes in defect morphology and dopant diffusion for Si implanted GaAs: Influence of ion energy and implant temperature

Conference · Thu Dec 01 04:00:00 EST 1994

OSTI ID:249039

Robinson, H G; Deal, M D ^[1]; Lee, C C ^[2]; Haynes, T E ^[3]; Allen, E L ^[4]; Jones, K S ^[5]

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1. Stanford Univ., CA (United States). Dept. of Electrical Engineering
2. Stanford Univ., CA (United States). Dept. of Materials Science
3. Oak Ridge National Lab., TN (United States)
4. San Jose State Univ., CA (United States). Dept. of Materials Engineering
5. Florida Univ., Gainesville, FL (United States). Dept. of Materials Science and Engineering

Experimental observations of dopant diffusion and defect formation are reported vs ion energy and implant temperature in Si-implanted GaAs. In higher energy implants (>100 keV), little or no diffusion occurs, while at energies less than 100 keV, the amount of dopant redistribution is inversely proportional to energy. Extended defect density shows the opposite trend, increasing with ion energy. Similarly, Si diffusion during post implant annealing decreases by a factor of 2.5 as the implant temperature increases from -2 to 40 C. In this same temperature range, maximum depth and density of extrinsic dislocation loops increases by factors of 3 and 4, respectively. Rutherford backscattering channeling indicates that Si- implanted GaAs undergoes an amorphous-to-crystalline transition at Si implant temperatures between -51 and 40 C. A unified explanation of the effects of ion energy and implant temperature on both diffusion and dislocation formation is proposed based on known differences in sputter yields between low and high energy ions and crystalline and amorphous semiconductors. The model assumes that the sputter yield is enhanced at low implant energies and by amorphization, thus increasing the excess vacancy concentration. Estimates of excess vacancy concentration are obtained by simulations of the diffusion profiles and are quantitatively consistent with a realistic sputter yield enhancement. Removal of the vacancy-rich surface by etching prior to annealing completely suppresses the Si diffusion and increases the dislocation density, lending further experimental support to the model.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 249039
• Report Number(s): CONF-941144--183; ON: DE96010642
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
CRYSTAL DEFECTS
DIFFUSION
GALLIUM ARSENIDES
ION IMPLANTATION
SILICON