DOPANT ELECTRICAL-ACTIVITY OF SI AND SI1-XGEX MULTILAYER STRUCTURES DOPED WITH DELTA-LIKE BORON SPIKES AT DIFFERENT TEMPERATURES

Boron spikes within multilayer structures of Si and of Si1-xGex deposited by means of molecular-beam epitaxy (MBE) at different temperatures have been investigated by secondary-ion-mass spectrometry (SIMS), spreading resistance, and Hall-effect measurements. For a Ge amount of x = 7% it is shown that segregation effects, electrical activity of B, steepness of B spikes, and solid solubility of B differ in Si and Si1-xGex at the same deposition temperatures. For Si1-xGex growth the. surface segregation is significantly reduced in comparison to the growth of Si layers. Steeper B profiles can be obtained at same temperatures but the amount of electrically inactive B is higher. Calculations of the charge-carrier distributions near the spikes have been performed using classical and quantum mechanical approaches to find out reasons for deviations of the concentration profiles of B and of holes obtained from SIMS and from spreading resistance measurements, respectively.