Depth profile of delta-doped semiconductors by X-ray reflection technique

Delta-doping is one of the methods to realize high concentration doping in semiconductors, by which the doped atoms are confined in the thin layer in semiconductor crystals. Sb and Er delta doping layers in silicon crystals w ere grown at different temperatures by silicon molecular beam epitaxy (MBE) . An oxygen ambient was also used in the Er delta doping process. Synchrotr on radiation X-ray reflection technique was employed to measure the dopant depth distribution. Results showed that the growth temperature should be be low 300 degrees C for obtaining narrow Sb or Er delta doping in order to av oid the surface segregation of Sb or Er atoms. Thermal stability of such de lta doped structure was also studied by this technique, no significant chan ge was observed in Sb delta doped Si crystal after annealing at 500 degrees C for 30 min. Besides, suppressing effect of surface segregation of dopant Er by oxygen was investigated. With the oxygen ambient, narrow Er delta do ping was realized at growth temperature of 400 degrees C, which was 100 deg rees C higher than that in the normal MBE epitaxy.