Arsenic-doped Si (001) gas-source molecular-beam epitaxy: Growth kinetics and transport properties

Arsenic-doped Si(001) layers with concentrations C-As up to 5 X 10(18) cm(- 3) were grown on Si(001)2 X 1 at temperatures T-s = 575-900 degrees C by ga s-source molecular-beam epitaxy (GS-MBE) using Si2H6 and AsH3. This is almo st an order of magnitude higher than the initially reported "maximum attain able'' saturated C-As value for GS-MBE from hydride precursors. At constant J(AsH3)/J(Si2H6), C-As decreases, while the film growth rate R-Si increase s, with T-s. Temperature programmed desorption measurements show that As se gregates strongly to the growth surface and that the observed decrease in C -As at high film growth temperatures is primarily due to increasingly rapid arsenic desorption from the segregated layer. Decreasing T-s enhances As i ncorporation. However, it also results in lower film growth rates due to hi gher steady-state As surface coverages which, because of the lone-pair elec trons associated with each As adatom, decrease the total dangling bond cove rage and, hence, the Si2H6 adsorption rate. At constant T-s, C-As increases , while RSi decreases, with increasing J(AsH3)/J(Si2H6). All incorporated A s resides at substitutional electrically active sites for concentrations up to 3.8X10(18) cm(-3), the highest value yet reported for Si(001):As growth from hydride source gases, and temperature-dependent electron mobilities a re equal to those of the best bulk Si:As. (C) 1999 American Institute of Ph ysics. [S0003-6951(99)04209-6].