Enhanced sticking coefficients and improved profile control using boron and antimony as coevaporated dopants in Si–MBE

Inefficient doping and poor profile control are generally associated with the use of coevaporated dopants in Si–MBE. However, two new techniques have been developed, one applicable to p‐type and the other to n‐type doping, which alleviate these problems. Coevaporated boron ( p‐type) is shown to have a simple incorporation mechanism by which good doping and profile control can be achieved using the conventional MBE technique of changing the source cell temperature. For n‐type doping, a method of enhancing the low incorporation efficiency of Sb has been found (potential enhanced doping) which is also ideally suited to profile control. Enhancements by a factor of up to 1000 times have been achieved. Material with bulklike mobilities has been obtained over the range of 1×1015 to 8×1019 cm−3 for p‐type and up to 3×1019 cm−3 for n‐type doping. Extremely sharp doping transitions down to <100 A/decade have been obtained.