Temperature-modulated Si(001): As gas-source molecular beam epitaxy: Growth kinetics and As incorporation

Arsenic doping at concentrations C-As equal to or greater than 10(18) cm(-3 ) during Si(001) growth from hydride precursors gives rise to strong As sur face segregation, low film growth rates R-Si, poor electrical activation, a nd surface roughening. Based upon the results of temperature-programmed des orption studies of Si(001):As surface processes during film deposition, we have investigated the use of temperature-modulated growth including periodi c arsenic desorption (10 s at 1000 degreesC) from the surface segregated la yer. Both constant-temperature and temperature-modulated Si(001):As layers were grown at T-s=750 degreesC, selected as a compromise between maximizing C-As and providing a usable deposition rate, by gas-source molecular beam epitaxy from Si2H6/AsH3 mixtures. For constant-temperature growth, R-Si is only 0.08 mum h(-1), the fraction of electrically active dopant is 55%, and film surfaces are very rough (rms roughness <w > =110 Angstrom). In sharp contrast, T-s-modulated layers exhibit increases in R-Si by 2.5 x to 0.20 m um h(-1), 100% electrical activity, and atomically smooth surfaces with <w > =2 Angstrom. The results are explained based upon the competition among A s surface segregation, desorption, and incorporation rates. (C) 2001 Americ an Institute of Physics.